Appendix:Dictionary of Mining, Mineral, and Related Terms/S/11

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See: stibiconite.


See: stibiconite.


An orthorhombic mineral, Sb (sub 2) S (sub 3) ; dimorphous with metastibnite; soft; metallic; may contain gold and silver; occurs in massive forms and in vertically striated prisms having perfect cleavage, in low-temperature veins and around hot springs; the chief source of antimony. Syn: antimonite; antimony glance; gray antimony; stibium. See also: stibnium.


An ancient name for "stibnite" used (as in Egypt) as a cosmetic for painting the eyes. See also: stibnite.


A trigonal mineral, Mg (sub 6) Cr (sub 2) (CO (sub 3) )(OH) (sub 16) .4H (sub 2) O ; hydrotalcite group; dimorphous with barbertonite; lilac colored; in Dundas, Tasmania, Australia; Transvaal, South Africa; Cunningsburgh, Shetland Islands; and Quebec, Canada.


A cartridge of explosive.


a. A small vein (a scrin) not wide enough for shoulder room, Derbyshire, U.K.

b. The selvage of mineralized country rock at the side of a vein. c. A rib or ore in a vein, or a small rake vein crossing the main vein, Derbyshire, U.K. d. U.K. A thin vein of ore or thin seam of clay in an ore vein.

sticking scrins

Eng. Small veins that do not afford shoulder room.

stick loading

A technique used in trench blasting, etc., in which a lower concentration of charge is obtained by placing wooden pegs between every cartridge in the hole thus halving the concentration.


See: standoff.


A term applied when drilling rock or a formation so soft that the drill bit tends to penetrate too rapidly and the circulation fluid is unable to clear the cuttings away fast enough to prevent their adhering to and compacting on the surfaces of the bit and other downhole drilling equipment and/or the borehole sidewalls. CF: balling formation; gummy.

sticky limit

The lowest water content at which a soil will stick to a metal blade drawn across the surface of the soil mass.

stiff clay

Clay of low plasticity.


A steel angle or bar riveted or welded across the web of a built-up girder to stiffen it.

stiff-fissured clay

A clay that is firm when dry at depth but is intersected by cracks through which water will seep easily. Clay deposits of this type are liable to slips on hillside slopes. Syn: slickensided clay.

stiff mud

A plastic mix of clay of very stiff consistency, as extruded from an auger machine.


The ability of a metal or shape to resist elastic deflection. For identical shapes, the stiffness is proportional to the modulus of elasticity.


Scot. Noxious gas resulting from an underground fire.


a. A monoclinic and triclinic mineral, Na (sub 2) Ca (sub 4) [Al (sub 10) Si (sub 26) O (sub 72) ].34H (sub 2) O ; zeolite group, with K replacing Na; forms sheaflike crystal aggregates and radiated masses in cavities in igneous rocks, as an alteration of plagioclase, or in hydrothermal veins.

b. Ger. See: heulandite.


a. An apparatus in which a substance is changed by heat into vapor, with or without chemical decomposition. The vapor is then liquefied in a condenser and collected in another part of the apparatus.

b. See: amalgam retort.

still coke

The residue left in the still on distilling crude shale oil to dryness.

stilling well

A chamber connected to a main body of water by a small inlet; such an arrangement is suitable for a recording gage.

Stillson wrench

The pipe wrench of common use, named for its inventor.



A monoclinic and triclinic mineral, K(Mg,Fe) (sub 8) (Si,Al) (sub 12) (O,OH) (sub 27) (?) ; black to green-black; in micalike plates, fibrous forms, and velvety bronze-colored incrustations. Syn: chalcodite.


A device to allow roadway steel arches a measure of yield under roof pressure to prevent buckling. The stilt may take the form of wooden extensions strapped to the legs of the arch, wire bags filled with dirt, a mechanical frictional appliance, or a hydraulic stilt. See also: yielding support.


a. A steel cylinder projecting beyond the face of a cutting bit that serves as a pilot or guide. See also: pilot.

b. The pneumatically actuated piston attached to a pointed rod that acts as a feed mechanism on a stoper drill.

stinger ream

To ream a borehole using a reaming bit equipped with a pilot or stinger.


Hot air and flame exhausted through openings in furnaces or tanks due to positive internal pressure.


A mining term for hydrogen sulfide. The gas has an unpleasant smell, resembling that of rotten eggs, hence the name. The presence of this gas may indicate a gob fire in its early stages. Produced by the distintegration of iron pyrites. See also: damp.


a. A British miner's term for inferior coal that stinks when burned.

b. A Welsh term for dolomite.


A variety of quartz that emits a fetid odor when struck.


See: stinkstone.


a. A stone that emits an odor on being struck or rubbed; specif. a bituminous limestone (or brown dolomite) that gives off a fetid smell (owing to decomposition of organic matter) when rubbed or broken. It may emit a sweet-and-sour smell if the carbonate rock is rich in organic-phosphatic material. See also: anthraconite; bituminous limestone. Syn: stinkstein.

b. Boulders of phosphate rock from Tennessee.


A fixed work target on the coalface that every collier is expected to do in one shift or a single week. In longwall conveyor work, it is the length, area, or volume of face that the miner regularly clears or loads out. Also called stent; cut. Syn: cut. See also: darg.


See: hitch.


An early name for nickel-bearing marcasite.


To fasten a timber by toenailing.

stitched canvas conveyor belt

A construction of conveyor belt made up of plies of cotton fabric stitched together. Stitched canvas belts may be untreated, impregnated, or coated. See also: belt.


Containing a random variable; word used to describe a system (e.g., sampling method) that has in it an element of randomness.


a. A rarely used term for a chimneylike orebody. Syn: pipe.

b. An irregular, metalliferous mass in a rock formation, such as a stock of lead ore in limestone. CF: boss.

stock craneman

Person who lifts and moves stock, such as limestone, scrap iron, or pig iron, for the open-hearth furnace.

stockhouse larryman

Person who drives an electric car to haul ore and limestone from the stockpiles to the blast furnace.

stocking conveyor

A belt conveyor in a blending system that receives bulk materials for delivery to the stacker conveyor.


a. An accumulation of ore or mineral built up when demand slackens or when the treatment plant or beneficiation equipment is incomplete or temporarily unequal to handling the mine output; any heap of material formed to create a reserve for loading or other purposes.

b. The ore accumulated at the surface when shipping is suspended. c. Material dug and piled for future use.


A mineral deposit consisting of a three-dimensional network of planar to irregular veinlets closely enough spaced that the whole mass can be mined. CF: reticulate. Syn: network deposit; stringer lode.


A space reserved on the surface near the materials shaft for the temporary storage of steel, timber, and other bulky items of supplies for mine use. The yard is surfaced and a mine car is used throughout.


With reference to a compound or a phase, pertaining to the exact proportions of its constituents specified by its chemical formula. It is generally implied that a stoichiometric phase does not deviate measurably from its ideal composition.


Unit of kinematic viscosity. The cgs unit of kinematic viscosity being that of a fluid that has a viscosity of 1 P (100 mPa.s) and a density of 1 g/cm (super 3) .


A hole, as in a reverberatory furnace, for introducing a rabble or other tool for stirring.


A mechanical appliance for feeding coal, coke, or other fuel into a boiler or furnace. In hand stoking, the person who shovels the fuel into the furnace is known as the stoker. See also: underfeed stoker; vibrating grate.

stoker coal

a. A screen size of coal specif. for use in automatic firing equipment.

b. This coal can be of any rank and the stoker is usually designed to fit the coal available. Factors of importance in the selection of coal for stoker use are size limits; size consist; uniformity of shipments; coking properties; ash-fusion characteristics; ash, sulfur, and volatile-matter percentages.


An orthorhombic mineral, CaSnSi (sub 3) O (sub 9) .2H (sub 2) O ; forms acute pyramids; at Roscommon Cliff, St. Just, Cornwall, U.K.

Stokes' law

a. A formula expressing the rates of settling of spherical particles in a fluid.

b. Gives the rate of fall of a small sphere in a viscous fluid. When a small sphere falls under the action of gravity through a viscous medium it ultimately acquires a constant velocity, V: V = 2ga (super 2) (d (sub 1) -d (sub 2) )/9eta where g is gravitational acceleration, a is the radius of the sphere, d (sub 1) and d (sub 2) are the densities of the sphere and of the medium, respectively, and eta is the coefficient of viscosity. V will be in centimeters per second if g is in centimeters per second per second; a will be in centimeters; d (sub 1) and d (sub 2) will be in grams per cubic centimeter; and eta will be in dynes second per square centimeter, or poises. c. The wavelength of light emitted by a fluorescent material is longer than that of the radiation used to excite the fluorescence. In modern language, the emitted photons carry off less energy than is brought in by the exciting photons; the details accord with the energy conservation principle. See also: elutriator; sedimentation test; terminal velocity. d. At low velocities, the frictional force on a spherical body moving through a fluid at constant velocity is equal to 6pi times the product of the velocity, the fluid viscosity, and the radius of the sphere. The wavelength of luminescence excited by radiation is always greater than that of the exciting radiation.

Stokes stretcher

The simplest type of stretcher used for underground first aid. This basket-type stretcher acts as a splint for the whole body, and is constructed of tubular steel and strong wire mesh. Used for lifting or lowering injured persons in difficult places. This type of stretcher is used in metal mines or in coal mines where the coalbed has a steep pitch. See also: stretcher.


See: continuous sintering.


A tetragonal mineral, 4[PbWO (sub 4) ] ; dimorphous with raspite; crystallizes in bipyramids; sp gr, 7.9 to 8.3; (super ) in oxidized zones of tungsten deposits.


A short wooden plug fixed in the roof, to which lines are hung, or to serve as a bench mark for surveys.


a. A mineral or group of consolidated minerals either in mass or in a fragment of pebble or larger size.

b. A stony meteorite. c. A cut and polished gem or other precious mineral (but not a synthetic compound used in ornamentation). d. Crushed or naturally angular particles of rock that will pass a 3-in (7.6-cm) sieve and be retained on a No. 4 U.S. Standard sieve.

stone band

See: dirt band.

stone bind

Eng. Interbedded layers of sandstone and shale, or for a rock (such as siltstone) intermediate between a sandstone and a mudstone.

stone butter

a. A variety of halotrichite. Syn: rock butter.

b. A variety of alum. c. A variety of clay.

stone clunch

Eng. Very hard underclay (clunch) with interbeds of sand.

stone coal

a. Wales. Anthracite, in lumps; also certain other very hard varieties of coal.

b. Mineral coal, as distinguished from charcoal; esp., in England, hard or anthracite coal. c. Sometimes applied to anthracite on account of its hardness. See also: anthracite. d. Early term for anthracite.

stone concentration

See: diamond concentration.

stone content

See: diamond content.

stone count

See: diamond count.

stone crane operator

a. In the quarry industry, a person who lifts blocks of stone and boxes of broken stone with a guy derrick in a quarry. Also called stone hoist operator.

b. In the stonework industry, one who lifts and moves blocks of stone with an electric bridge crane in a stone mill.


a. Person whose occupation is cutting stone; a stone mason.

b. A gem cutter. c. A machine for facing stone.

stone drift

A drift excavated in rock, such as from the surface down to a coal seam. See also: hard heading; rock drivage; slant.

stone dust

a. In coal mines any inert dust spread on roadways as a defense against the danger of coal dust explosions. The stone dust used is of a type that does not cake in mine air. Ground limestone is satisfactory in most conditions. About 5% less limestone is required than shale, and gypsum has about two to three times the efficiency of shale. Gypsum appears to owe its high efficiency to its hydrate water. Inert dusts are effective because they absorb heat that the coal dust would otherwise receive from the flame. See also: dust consolidation.

b. Shale dust. c. Loosely applied to any incombustile dust used to render coal dust incombustible.

stone-dust barrier

A device erected at strategic points in mine roadways for the purpose of arresting explosions. Consists essentially of trays loaded with stone dust, which are upset or overturned by the pressure wave in front of an explosion ahead of the flame, producing a dense curtain or cloud of inert dust to blanket the flame and stop further propagation of the explosion. See also: colliery explosion; flame inhibitor.

stone duster

The person in charge of stone dusting in coal mines.

stone dusting

The systematic distribution of stone dust along mine roadways to cover the coal dust and reduce its flammability. Although stone dusting may not always stop an explosion, it is less violent with stone dusting than without. Safety regulations in many countries require that stone dust be applied either mixed with the coal dust along mine roadways or as stone dust barriers, to reduce the liability of coal-dust explosions.

stone exposure

See: diamond exposure.

stone fields

See: block field.

stone flax

An early name for asbestos.

stone gobber

In bituminous coal mining, person who removes stone and other refuse from coal mine floors and dumps refuse into mine cars for disposal.

stone hammer

A hammer for breaking or dressing stone.


a. U.K. A heading driven in stone or bind.

b. The solid rock first met in sinking a shaft. c. See: bedrock.

stone intrusion

Irregular masses of sandstone occurring within a coal seam or penetrating the seam from top to bottom, sometimes much distorted, but always connected with a similar sandstone in the roof or higher strata. Also called stone eye. See also: drop.

stone land

An area that is economically valuable for some variety of stone, such as granite or sandstone, that can be quarried. CF: mineral land.


a. A miner employed on stonework. See also: ripper.

b. A worker who drills shotholes in rock in readiness for firing by the shotfirer.

stone mill

a. A stone crusher.

b. A machine for dressing and finishing marble, slate, etc.; a stone dresser.

stone mine

a. Scot. An ironstone mine or working.

b. Scot. A mine driven in barren strata.

stone ocher

Ocher found in hard globular masses.

stone of ore

A piece of ore.

stone per carat

The number of near-equal-size diamonds the weight of which is 1 carat, hence a relative measure of the size of diamonds. Syn: diamonds per carat.

stone pit

A quarry where stones are dug.

stone planer

In the concrete products and stonework industry, person who shapes, smooths, squares, and removes excess material from the surfaces of blocks or slabs of building or ornamental stone (limestone, slate, sandstone, marble, and such concrete work as imitation marble) on a planer. Also called planer hand; planer man; planer operator; planing machine operator.

stone polisher

In the stonework industry, person who polishes to a high luster by hand methods those curbed, irregular, and straight surfaces of blocks and slabs of marble and granite that cannot be polished by machine. May be designated according to kind of stone, such as granite polisher or marble polisher. Also called stone finisher.

stone pressure

See: diamond pressure.


a. Detached particles of rock usually smaller than 10 in (25 cm) in diameter. Stones are classed as gravel on bottom sediment charts.

b. In mica, small embedded crystals or holes resulting from stones. Also called stone holes.

stone saw

A stone-cutting apparatus having no teeth, being a simple iron band fed with sand and water, cutting by attrition.

stone sawyer

Person who cuts stone.

stone sill

Cumb. Sandy fireclay. CF: sill.

stone spavin

York. Usually a stone bind or sandstone with rootlets.

stone tubbing

Watertight stone walling of a shaft cemented at the back.

stone wall

See: hogback.

stoneware clay

A clay suitable for manufacture of stoneware (ceramic ware fired to a hard, dense condition and with an absorption of less than 5%); used for items such as crocks, jugs, and jars. It possesses good plasticity, fusible minerals, and a long firing range.

stone weight

See: diamond content.


a. All underground work involving the excavation, loading, or handling of rock or dirt, such as ripping, dinting, tunneling, packing, etc. In thin coal seams, stonework is a major cost item. See also: dead work.

b. The process of working in stone; the shaping, preparation, or setting of stone.

stone yellow

See: yellow ocher.

stony clunch

Eng. Compressed clays with sandstone layers interspersed, Midlands.


The last stump or corner block of coal left when extracting pillars by means of lifts, in pillar methods of working.


a. The point where a miner stops digging downward to work outward.

b. The assembly carrying the return rollers and brackets for connecting standard sections together in belt conveyors.


Eng. Applied to a vein cut vertically for some distance.

stool end

A supporting pillar mine.


See: bord-and-pillar.


A miner in pillar methods of working employed in pillar robbing; a practice now obsolete.


A passageway, the height of which requires a person to stoop or crouch in traversing it.


a. Any cleat or beam to check the descent of a cage, car, pump, pump rods, etc.

b. In mining, a variation of stope.


A simple arrangement of two stout timbers, sliding on pivots, one of which can be placed across the track rail and held in position by the other block. They are often used on haulage landings to prevent trams running down the incline uncontrolled. Syn: nubber.


a. An excavation from which ore has been removed in a series of steps. A variation of step. Usually applied to highly inclined or vertical veins. Frequently used incorrectly as a syn. for room, which is a wide-working place in a flat mine.

b. To excavate ore in a vein by driving horizontally upon it a series of workings, one immediately over the other, or vice versa. Each horizontal working is called a stope because when a number of them are in progress, each working face under attack assumes the shape of a flight of stairs. When the first stope is begun at a lower corner of the body of ore to be removed, and, after it has advanced a convenient distance, the next is commenced above it. This is called overhand stoping. When the first stope begins at an upper corner, and the succeeding ones are below it, it is called underhand stoping. The term stoping is loosely applied to any subterranean extraction of ore except that which is incidentally performed in sinking shafts, driving levels, etc., for the purpose of opening the mine. c. Commonly applied to the extraction of ore, but does not include the ore removed in sinking shafts and in driving levels, drifts, and other development openings. d. The working above and below a level where the mass of the orebody is broken. A stope is the very antithesis of a shaft, tunnel, drift, winze, or other similar excavation in a mine. e. Any excavation in a mine, other than development workings, made for the purpose of extracting ore. The outlines of the orebody determine the outlines of the stope. The term is also applied to breaking ground by drilling and blasting or other methods. See also: caving. f. A body of mineral left by running drifts about it.

stope board

A timber staging on the floor of a stope for setting a rock drill. The stage is tilted to enable the bottom holes being drilled in the same inclined direction.

stope development

The driving of subsidiary openings designed to prepare blocks of ore for actual extraction by stoping.

stope driller

In metal mining, one who operates compressed air, percussion-type rock drill in a stope (an underground opening from which ore is extracted in a series of steps). Also called stoper.

stope fillings

Broken mullock or rock or the broken low-grade portion of a lode or vein used to fill stopes on abandonment.

stope hoist

A small portable compressed-air hoist for operating a scraper-loader or for pulling heavy timbers into position, often used in narrow stopes.

stope miner

See: miner.

stop end

The shuttering erected at the end of a length of concrete construction and shaped to provide a suitable joint for the next length.

stope pillar

A column of ore left to support the stope.


a. A stoping drill.

b. A light percussive drill incorporating a pneumatic cylinder to provide support and thrust while drilling steeply upward. c. See: stope driller.


See: roof bolter.

stope sampling

The sampling of exposure in the stopes, or of material coming from the stopes. This type of sampling permits a closer control of the grade of ore being won and is conducted largely at the working place or stope.

stope scraper

In metal mining, one who shovels or rakes ore into mine cars in a stope (an underground opening in a vein from which ore is extracted in a series of steps). Syn: hand scraper.

stope washings

In gold mines, auriferous slimes washed down from the floor (footwall) of the stope and sent to the mill.


a. The act of excavating rock, either above or below a level, in a series of steps. In its broadest sense rock stoping means the act of excavating rock by means of a series of horizontal, vertical, or inclined workings in veins or large, irregular bodies of ore, or by rooms in flat deposits. It covers the breaking and removal of the rock from underground openings, except those driven for exploration and development. The removal of ore from drifts, crosscuts, shafts, winzes, and raises, which are excavated to explore and develop an ore deposit, is incidental to the main purpose for which stopes are driven and is not a stoping operation. Exploratory and development openings are driven to prepare a mine for extraction of the ore by stoping. See also: stope.

b. In civil engineering, an enlargement. c. The loosening and removal of ore in a mine either by working upward (overhead or overhand) or downward (underhand).


See: overhand stoping.

stoping drill

A small air or electric drill, usually mounted on an extensible column, for working stopes, raises, and narrow workings.

stoping ground

Part of an orebody opened by drifts and raises, and ready for breaking down.

stoping in horizontal layers

See: overhand stoping.

stoping methods

The classification of stoping methods adopted by the U.S. Bureau of Mines, devised largely on the basis of rock stability, is as follows: (1) stopes naturally supported--this includes open stoping with open stopes in small orebodies, and sublevel stoping; and open stopes with pillar supports that includes casual pillars and room (or stope) and pillar (regular arrangement); (2) stopes artifically supported--this includes shrinkage stoping, with pillars, without pillars, and with subsequent waste filling; cut-and-fill stoping; stulled stopes in narrow veins; and square-set stoping; (3) cave stopes--this includes caving (ore broken by induced caving), block caving, including caving to main levels and caving to chutes or branched raises; sublevel caving and top slicing (mining under a mat that, together with caved capping, follows the mining downward in successive stages); and (4) combinations of supported and caved stopes (as shrinkage stoping with pillar caving, cut-and-fill stoping with top slicing of pillars, etc.)

stoping underhand

Mining a stope downward in such a series that presents the appearance of a flight of steps.

stoping width

a. Width of lode broken during mining, including any barren rock.

b. Used in underground sampling and is estimated from direct measurement behind the stope face and reduced to allow for any waste stowed. With wide tabular deposits, there is little difference between the stoping width and the clean width.


To close off part of a mine by means of a brattice, wall, stopping, etc.

stopper hole

In a puddling furnace, the hole through which the rabble is introduced.

stopper maker

One who forms and finishes fire clay stoppers for open hearth ladles, using a stopper press and a finishing machine.


a. A brattice, or more commonly, a masonry or brick wall built across old headings, chutes, airways, etc., to confine the ventilating current to certain passages, and also to lock up the gas in old workings, and in some cases to smother a mine fire.

b. A permanent wall built to close off unused crosscuts to prevent the air from short circuiting. c. A dam or seal to isolate old workings containing water or injurious gases. See also: dam; inrush of water. Syn: ventilation stopping.

stopping builder

In bituminous coal mining, one who builds walls of concrete, stone, or brick and mortar, to close off old passageways or haulageways underground, to maintain ventilation in new workings.

storage battery locomotive

An underground locomotive powered by storage batteries.

Storrow whirling hygrometer

A hygrometer in which the two thermometers are mounted side by side on a brass frame and fitted with a loose handle so that it can be whirled in the atmosphere to be tested. The instrument is whirled at some 200 rpm for about 1 min and the readings on the wet- and dry-bulb thermometers recorded; used in conjunction with Glaisher's or Marvin's hygrometrical tables. It gives more consistent and accurate results than the ordinary instrument. See also: whirling hygrometer.


a. A tetragonal mineral, FeGe(OH) (sub 6) ; greasy; at Tsumeb, Namibia.

b. The mineral group jeanbandyite, mopungite, stottite, and tetrawickmanite.


a. A large steel furnace or oven connected with the blast furnace to preheat the blast before it is introduced into the furnace proper.

b. A kiln, as for firing pottery or drying minerals.

stove coal

a. In anthracite only; two sizes of stove coal are made, large and small. Large stove, known as No. 3, passes through a 2-1/4- to 2-in (5.7- to 5-cm) mesh and over a 1-7/8- to 1-1/2-in (4.8- to 3.8-cm) mesh; small stove, known as No. 4, passes through a 1-7/8- to 1-3/8-in (4.8- to 3.5-cm) mesh and over a 1-1/8- to 1-in (2.9- to 2.5-cm) mesh. Only one size of stove coal is now usually made. It passes through a 2-in (5-cm) square mesh and over a 1-3/8-in (3.5-cm) square mesh.

b. See: anthracite coal sizes.

stoved salt

Stoved open-pan salt.


Riveted-seam or spiral-welded-seam, thin-wall pipe used as a conductor, standpipe, or casing in a borehole.

stovepipe casing

See: stovepipe.


a. To pack away rubbish into goaves or old workings.

b. To gob; to fill the waste; to put debris into the waste.


Scot. In longwall mining the space from which the mineral has been extracted and which has been filled with waste.


Derb. A wooden landmark, placed to indicate possession of mining ground. Also spelled stowse.


a. A method of mining in which all the material of the vein is removed and the waste is packed into the space left by the working.

b. The debris of a vein thrown back of a miner and which supports the roof or hanging wall of the excavation. c. See: solid packing.

stowing method

Any of several methods of working coal or ore deposits in which systematic stowing of the worked out areas is part of the system. See also: coal mining methods; solid stowing; strip packing.


A vertical mine timber, esp. one supporting a set in a shaft.

straddle spread

See: split spread.


From the German "strahlstein." (radiating stone), the original name for actinolite (Greek "aktis" radiating). See also: actinolite.


Common term for straight brick, as a 9-in (23-cm) straight.


In stripping, a pit that follows a straight line when projected on a horizontal plane.

straight chopping bit

See: chopping bit.

straight-cut gang frame

In quarrying, a saw gang that slides back and forth on a bed, as contrasted with the ordinary saw gang that swings back and forth when suspended from above.

straight dynamites

Dynamites composed of nitroglycerin, a combustible such as wood meal, sodium nitrate, and an antacid, such as calcium or magnesium carbonate, and are made in 15% to 60% strength, the percentage representing the proportion of nitroglycerin in the dynamites. They are powerful, quick acting, and fairly water resistant, but on detonation produce poisonous gases, esp. in the higher grades. Their relatively high cost, sensitivity to shock and friction, and high flammability, together with the dangerous fumes developed, make them less suitable for general use than more recently developed modifications.

straightedge leveling

A system of leveling using a straightedge and a spirit level.

straight girder support

An H-section girder used as a roadway or face beam support. The girder for spanning roadways is commonly 6 in (15.2 cm) deep and 5 in (12.7 cm) in width of flange. It is supported by wood or steel props or by brick or concrete sidewalls, the roof being made secure by timber or sheet lagging. Channel section girders are also used in special cases. See also: steel support.

straight point

Aust. That straight portion of the inner main rail between the rails of a turnout.

straight-side core bit

See: straight-wall bit.

straight stall

A lateral excavation into a thick seam of coal. Also called straight coal.

straight-type wedge

A plain deflecting wedge, not equipped with a rose or stabilizing ring.

straight-wall bit

An annular-shaped (core) bit the inner walls of which are parallel with the outer walls and not tapered to receive a core lifter. Syn: straight-side core bit.

straight-wall core shell

a. A reaming shell the outside walls of which are straight and not set with diamonds or hard-metal reaming points.

b. Sometimes used as a syn. for blank reaming shell.

straight work

a. Narrow headings in coal.

b. A method of working coal by driving parallel headings and then removing the coal between them.


a. Change in the shape or volume of a body as a result of stress; a change in relative configuration of the particles of a substance. Syn: deformation.

b. Deformation resulting from applied force; within elastic limits strain is proportional to stress. CF: stress. c. A measure of the change in the size or shape of a body, referred to its original size or shape. Linear strain is the change per unit length of a linear dimension. True strain (natural strain) is the natural logarithm of the ratio of the length at the moment of observation to the original gage length. Conventional strain is the linear strain referred to the original gage length. Shearing strain (shear strain) is the change in angle (expressed in radians) between two lines originally at right angles. When the term strain is used alone, it usually refers to the linear strain in the direction of the applied stress. See also: true strain. d. There are, generally speaking, two kinds of strains: normal and shear. Normal strains are those that may result in the relative displacement of two particles along the line joining those particles, whereas in shear strains, the particles are displaced at a right angle to the line joining them. All possible deformations may be represented as a combination of these two types of strain.

strain bar

An instrument well suited for measuring the strain on a rock face. It consists essentially of an invar steel bar with a fixed point at one end and a movable point attached to a rider at the other end. The rider may be moved along the bar between two stops, and the extent of movement is indicated by a dial gage attached to the bar.

strain break

Fractures occurring in rock quarries where the rock is under compressive stress. This stress is relieved locally in the process of quarrying, resulting in the rending or fracturing of the rock mass.

strain burst

Rock burst in which there is spitting, flaking, and sudden fracturing at the face, indicating increased pressure there.

strain cleavage

See: slip cleavage.

strain ellipsoid

In elastic theory, a sphere under homogeneous strain is transformed into an ellipsoid with this property; the ratio of the length of a line, which has a given direction in the strained state, to the length of the corresponding line in the unstrained state, is proportional to the central radius vector of the surface drawn in the given direction. The ellipsoid whose half axes are the principal strains. CF: reciprocal strain ellipsoid.

strain gage

a. A general term for a device with which mechanical strain can be measured, commonly by an electrical signal, e.g., a wire strain gage.

b. An electrical, mechanical, or optical device for measuring movement of rock, cumulative loading of support props, opening cracks, etc. c. An electromechanical device that transforms small displacements to changes in resistance that are proportional to the displacement. Strain gages are used in ocean bottom pressure measuring equipment.

strain relief method

A technique for the determination of absolute (total) strain and stress within rock in situ. In this method, a smooth hole is bored in the rock and a gage is inserted to measure diametral deformation. The hole is then overcored with a large coring bit so that the cylinder of rock containing the deformation measuring gage is free to expand. The change in the diameter of the hole when the rock cylinder is free to expand is a function of the original stress in the rock and its elastic modulus.

strain restoration method

A technique for the determination of absolute (total) strain and stress within rock in situ. This method involves (1) installation of strain gages on the rock surface; (2) cutting of a slot in the rock between the strain gages so that the surface rock is free to expand; (3) installation of a "flat-jack" (hydraulic pressure cell) in the slot; and (4) application of hydraulic pressure to the flat jack until the rock is restored to its original state of strain. The original stress in the rock is presumed to be equal to the final pressure in the flat jack.

strain rosette

At any point on the surface of a stressed body, strains measured on each of three properly chosen intersecting gage lines make possible the calculation of the principal stresses at that point. Such gage lines, and the corresponding strains, are called a strain rosette.

strain sheet

a. A skeleton drawing of a structure, as a roof of truss or a bridge, showing the stress to which each member will be subjected.

b. A quarryman's term for granite sheets produced by compressive strain.

strain-slip cleavage

See: false cleavage; slip cleavage.

Straits tin

One of the purest commercial forms of tin (99.89% purity) produced from alluvial ores in Malaysia.

strait work

See: straight work.


a. A relatively wide launder or sluice set at a slope and covered with a blanket or corduroy for catching comparatively coarse gold and valuable mineral. See also: blanket strake.

b. A trough in which ore, gravel, etc., are washed; a launder. c. The place where ore is assorted on the floor of a mine; a dressing floor.


Term for wire rope with one or more broken strands.

stranded rope

See: preformed rope; multistrand rope; flattened strand rope.


A triclinic mineral, (Zn,Cu) (sub 3) (AsO (sub 4) ) (sub 2) ; blue; at Tsumeb, Namibia.


a. A bar; a beam; a coal face bar.

b. A thin bar or metal plate, similar to a fishplate, used to secure together butt-jointed timber or steel members.

strap brake

A brake generally used on small winding engines.

strap fishplates

Flattened bars of iron with holes punched through them for bolts. The holes are made somewhat larger than the bolt to permit rail expansion and contraction.

strap-rope haulage

A system of haulage (usually endless rope) in which the engine is installed on the surface, and the power is transmitted to the haulage drums at the pit bottom by means of a rope, which is known as a strap rope, or a driving rope. This rope merely transmits power and is distinct from the haulage rope.


Thin metal support members from 5 to 20 ft (1.5 to 6 m) long are bolted to the mine roof to prevent roof deterioration between the bolts. Also known as roof mats or bacon skins.


Plural of stratum.

strata bolt

A bolt or rod, from 2 to 5 ft (0.6 to 1.5 m) or more in length, set in drill holes in the strata for the support of curbs, skeleton tubbing, helical steel supports, etc., in shafts and staple shafts. In general, the weaker the ground, the longer the bolts. CF: roof bolting.


Said of a mineral deposit confined to a single stratigraphic unit. The term can refer to a stratiform deposit, to variously oriented orebodies contained within the unit, or to a deposit containing veinlets and alteration zones that may or may not be strictly conformable with bedding.

strata control

See: roof control.

strata gases

These occur in the mineral deposit itself or in adjacent or nearby formations. Their origin may be in a particular formation in which they were laid down or formed subsequently by chemical action, or they may occasionally migrate into other formations, frequently because of release of pressure with mining. Water flow and rock porosity and fissures also allow gas migration. The principal strata gases are methane, carbon dioxide, nitrogen, sulfur dioxide, hydrogen sulfide, and radon.


An apparatus inserted in the drill hole that permits engineers to make a visual inspection of the strata.

strata temperature

The strata temperature is determined by the surface temperature, the diffusivity of the strata, and the emissivity of the surface. With rocks of high thermal conductivity, and thus, high diffusivity, as in metal mines, the increase in temperature with depth is small, i.e., the geothermic gradient is low. Where rocks have low thermal conductivity, as in coal measure strata, the geothermic gradient is steep. Syn: geothermic gradient.

strategic and critical material

Materials that (a) would be needed to supply the military, industrial, and essential civilian needs of the United States during a national emergency, and (b) are not found or produced in the United States in sufficient quantities to meet such need.

strategic mica

Ruby and nonruby block mica. Good-stained or better qualities, grade No. 6 or larger; ruby-stained A/B quality, grade No. 6 or larger; ruby and nonruby film, first and second qualities, grade No. 4 and smaller; muscovite and phlogopite splittings; and phlogopite block of high heat quality.

strategic minerals

Minerals essential to the national defense, for the supply of which, during war, we are wholly or in part dependent on foreign sources, and for which strict measures controlling conservation and distribution are necessary. For example, chromium- and tin-bearing minerals, quartz crystal, and sheet mica were some of the "strategic minerals" during World War II.


Characterized by numerous very thin parallel layers, whether separable or not, either of sedimentary deposition (as a bed of clay) or of deposition from solution (as in a stalagmite or banded agate).


a. The formation, accumulation, or deposition of material in layers; specif. the arrangement or disposition of sedimentary rocks in strata. See also: bedding.

b. A structure produced by deposition of sediments in strata; a stratified formation, or stratum. It may be due to differences of texture, hardness, cohesion or cementation, color, internal structure, and mineralogic or lithologic composition. c. The state of being stratified; a term describing a layered or bedded sequence, or signifying the existence of strata. d. A structure produced by deposition of sediments in beds or layers (strata), laminae, lenses, wedges, and other essentially tabular units.

stratification of methane

In relatively unventilated cavities in coal mines, such as wastes, it is frequently found that the methane percentage or concentration is higher at roof level, lower at midheight, and least at floor level. This is termed stratification of methane. See also: combustible gases layer.

stratification plane

See: bedding plane; stratification of methane.


Formed, arranged, or laid down in layers or strata; esp. said of any layered sedimentary rock or deposit. See also: bedded.

stratified rock

See: sedimentary rock.

stratified rocks

a. Derivative or stratified rocks may be fragmental or crystalline; those that have been mechanically formed are all fragmental; those that have been chemically precipitated are generally crystalline; and those composed of organic remains are sometimes partially crystalline. Syn: sedimentary rocks.

b. Rocks arranged in layers.


a. Said of a special type of strata-bound deposit in which the desired rock or ore constitutes, or is strictly coextensive with, one or more sedimentary, metamorphic, or igneous layers; e.g., beds of salt or iron oxide, or layers rich in chromite or platinum in a layered igneous complex.

b. Having the form of a layer, bed, or stratum; consisting of roughly parallel bands or sheets, such as a stratiform intrusion. Incorrect spellings: strataform, stratoform. c. Bedded or layered.


A geologist who specializes in stratigraphy.


Pertaining to the composition, sequence, and correlation of stratified rocks.

stratigraphic classification

The arbitrary, but systematic arrangement, zonation, or partitioning of the sequence of rock strata of the Earth's crust into units with reference to the many different characters, properties, or attributes that the strata may possess (Hedberg, 1958).

stratigraphic control

a. The influence of stratigraphic features on ore deposition, e.g., ore minerals selectively replacing calcareous beds. CF: structural control.

b. The degree of understanding of the stratigraphy of an area; the body of knowledge that can be used to interpret its stratigraphy or geologic history.

stratigraphic geology

See: stratigraphy.

stratigraphic heave

a. For normal faults, the width of the gap between two parts of a disrupted bed, measured in the direction of the faulted bedding plane.

b. For reverse faults, the width of the overlap between two parts of a disrupted bed, measured in the direction of the faulted bedding plane.

stratigraphic hole

A borehole drilled specif. to obtain a detailed record of the character and composition of the rock formation penetrated and not for the purpose of locating a mineral deposit. See also: record hole.

stratigraphic section

See: geologic section.

stratigraphic separation

The thickness of the strata that originally separated two beds brought into contact at a fault. Syn: stratigraphic throw.

stratigraphic sequence

A chronologic succession of sedimentary rocks from older below to younger above, essentially without interruption; e.g., a sequence of bedded rocks of interregional scope, bounded by unconformities.

stratigraphic throw

See: stratigraphic separation; throw.


a. The science of rock strata. It is concerned not only with the original succession and age relations of rock strata but also with their form, distribution, lithologic composition, fossil content, geophysical and geochemical properties; indeed, with all characters and attributes of rocks as strata; and their interpretation in terms of environment or mode of origin, and geologic history. All classes of rocks, consolidated or unconsolidated, fall within the general scope of stratigraphy. Some nonstratiform rock bodies are considered because of their association with or close relation to rock strata. Syn: stratigraphic geology.

b. The arrangement of strata, esp. as to geographic position and chronologic order of sequence. c. The sum of the characteristics studied in stratigraphy; the part of the geology of an area or district pertaining to the character of its stratified rocks. d. A term sometimes used to signify the study of historical geology. e. That branch of geology that treats of the formation, composition, sequence, and correlation of the stratified rocks as parts of the Earth's crust. f. That part of the descriptive geology of an area or district that pertains to the discrimination, character, thickness, sequence, age, and correlation of the rocks of the district.

stratometric survey

A system whereby the in situ orientation of a core sample can be reproduced on the surface. A line is inscribed on the smoothed bottom of a borehole, and its azimuth relationship with a compass direction photographically recorded. When cored and removed from the borehole, the inscribed line can be used as a guide in orienting the core on the surface.


a. A bed or layer of rock; strata, more than one layer.

b. A layer greater than 1 cm in thickness. c. A tabular or sheetlike body or layer of sedimentary rock, visually separable from other layers above and below; a bed. The term is more frequently used in its plural form, strata. CF: lamina.

stratum plain

See: stripped plain.

straw boss

A generic term that sometimes includes all supervisory officials in a mine; a supervisor of a small group of miners usually working under a certified foreman.

stray current

a. The use of direct current electric power in most coal mines presents a problem of corrosion caused by an electrolytic action on pipes. Where the track is employed as a conductor of electricity in this type of power system, the voltage drop produces a difference in potential between the track and earth or other structures that may serve as a conductor, such as pipelines. This condition may cause an electric current to flow in pipelines that form a parallel path with the track system.

b. Electric current that is introduced in the earth by leakage of industrial currents.


a. The color of a mineral when scraped on a white ceramic plate.

b. The color of a mineral powder usually obtained by scratching with steel or by rubbing on unglazed porcelain; it is more diagnostic for identification than bulk mineral color. c. A long, narrow, irregular stretch of land or water. d. A comparatively small and flattish or elongate sedimentary body, visibly differing from adjacent rock, but without the sharp boundaries typical of a lens or layer. e. A long, narrow body of sand, perhaps representing an old shoreline; a shoestring. f. The outcropping edge of a coal bed.


See: mineral streaking.

streak plate

In mineral identification, a piece of unglazed porcelain, hardness about 7 on the Mohs scale, used for rubbing a sample to obtain its powder color, or "streak."

stream-down sluice

A sluice box placed to receive the material rejected from the tables of a dredge.

stream gold

Gold in placer deposits of alluvial origin.


a. Separating ore from gravel by the aid of running water.

b. The working of alluvial deposits for the tin found in them; the washing of tin ore from the detrital materials; also, the reduction of stream tin. c. A property that combustible gas possesses as a result of its low density. If, in a sloping roadway having a smooth roof, combustible gas is released from a break at the lower end, the gas will cling to the roof and stream upwards forming a pool at the upper end. Pure streaming and diffusion can occur where the air currents are sluggish or nonexistent, such as in wastes that have not collapsed, and roadways of large cross-sectional area in which the ventilation air speed is low.

streaming potential

Potential difference between a permeable diaphragm and the liquid passing through it.


A hypothetical line that shows the velocity direction of the fluid stream at each point along the line. Streamlines do not therefore cross each other. A set of streamlines charts the flow pattern. If the flow is steady then the streamline pattern does not change with time. If, however, the streamlines are continually changing shape the flow is unsteady.

streamline flow

See: laminar flow.


This involves the placing of fairing around or over obstructions to airflow, in such a way as to change that flow from turbulent to laminar.

stream tin

Cassiterite occurring as waterworn pebbles in alluvial or placer deposits. CF: lode tin. Syn: alluvial tin.

stream tube

A tube of fluid the enveloping surface of which consists of streamlines.


a. Corn. A name given by miners to alluvial tin deposits usually worked in the open air.

b. A place where ore, generally tin ore, is washed from alluvial deposits.


Ger. The longwall system of coal mining.

street ell

A pipe elbow with male threads on one end, female on the other.


Corn. A trough for washing tin ore. A variation of strake.


a. An orthorhombic mineral, FePO (sub 4) .2H (sub 2) O ; variscite group; forms a series with variscite; may have Mn replacing Fe; dimorphous with phosphosiderite; pale red.

b. The mineral group mansfieldite, scorodite, strengite, and variscite.


The stress at which a rock ruptures or fails.

strength of materials

The number of amperes flowing through a circuit. Analogous to the flow of gallons per minute in a water pipe. ` /�~ *�~ ����� � � DICTIONARY TERMS:strength of materials The science that deals with t The science that deals with the effects of forces in causing changes in the size and shape of bodies.


In a solid, the force per unit area, acting on any surface within it, and variously expressed as pounds or tons per square inch, or dynes or kilograms per square centimeter; also, by extension, the external pressure that creates the internal force. The stress at any point is mathematically defined by nine values: three to specify the normal components and six to specify the shear components, relative to three mutually perpendicular reference axes. CF: strain. See also: normal stress; true stress; shear stress.

stress analysis

Determination of the stresses in the component parts of a structure when subjected to load. See also: photoelasticity.

stress circle

A Mohr circle that reveals the distribution of stress.

stress-corrosion cracking

Failure by cracking under combined action of corrosion and stress, either external (applied) or internal (residual). Cracking may be either intergranular or transgranular, depending on metal and corrosive medium.

stress diagram

See: stress-strain diagram.

stress difference

The difference between the greatest and least of the three principal stresses.

stress envelope

The zone of extra stress around a cylindrical hole being actually cylindrical in form. Syn: ring stress.

stress field

The state of stress, either homogeneous or varying from point to point, in a given domain.

stress meter

An instrument designed to measure pressure changes within rock as a result of mining operations. The instrument consists of a tongue of steel containing a groove filled with glycerin. When pressure is exerted upon the external surface of the tongue, the glycerin is partially squeezed from the groove and exerts pressure on a diaphram, which accordingly bulges outwards. A strain gage is cemented on the outer wall of the diaphragm, and as the curvature increases and the gage is strained, so does its resistance vary.

stress mineral

A term suggested for minerals such as chlorite, chloritoid, talc, albite, epidote, amphiboles, and kyanite, whose formation in metamorphosed rocks is favored by shearing stress. CF: antistress mineral.

stress-number (S-N) curve

A curve obtained in fatigue tests by subjecting a series of specimens of a given material to different ranges of stress and plotting the range of stress against the number of cycles required to produce failure. In steel and many other metals, there is a limiting range of stress below which failure will not be produced even by an indefinite number of cycles.

stress ring

Stress rings are force lines drawn on the cross section of an excavation to indicate the distribution of the additional stress in the rock caused by that excavation.

stress solid

The solid figure formed by surfaces bounding vectors drawn at all points of the cross section of a member and representing the unit normal stress at each such point. The stress solid gives a picture of the stress distribution on a section.

stress-strain curve

A curve similar to a load extension curve, except that the load is divided by the original cross-sectional area of the test piece and expressed as tons or pounds per square inch, while the extension is divided by the length over which it is measured and expressed in inches per inch. See also: load-extension curve.

stress-strain diagram

a. A graph on which is plotted stress vs. strain. Such a graph may be constructed in any test during which frequent or continuous measurements of both stress and strain are made. It is commonly constructed for the compression, tension, and torsion tests. It is usually necessary for the determination of deformation energy, elastic limit, modulus of elasticity, modulus of rigidity, proportional limit, and yield strength. It is often useful in determination of elongation, modulus of rupture, ultimate strength and related properties.

b. The curve obtained by plotting unit stresses as ordinates against corresponding unit strains as abscissas. Syn: stress diagram.

stress trajectory

A line (in a stressed body) tangent to the direction of one of the principal stresses at every point through which it passes. Syn: isostatic.

stress zone

This is the zone of additional stress in the rock surrounding and caused by a stoped area.


The system of mining coal by headings or narrow work. See also: bord-and-pillar. Also spelled strett.


A particular direction or course; as, the stretch of a coal seam.


a. A bar used for roof support on a roadway, which is either wedged against or pocketed into the sides of the roadway and not supported by legs or struts.

b. A bar fixed across a narrow working place or tunnel to support a rock drill. c. A main backing deal or longitudinal bar in contact with three or more support bars or girders.


In shaft-sinking, the crosspieces holding the walling apart.

stretch fault

See: stretch thrust.

stretch thrust

A little-used term for a reverse fault formed by shear in the inverted limb of an overturned fold. Syn: stretch fault.


a. One of a series of parallel straight lines on the surface of a crystal, as in pyrite, indicative of an oscillation between two crystal forms; also, one of a series of such lines on the cleavage planes of a mineral, as of plagioclase, calcite, or corundum, indicative of polysynthetic twinning. Syn: striation. Pl: striae.

b. Striation. c. A minute groove or channel; a threadlike line or narrow band (as of color) esp. when one of a series of parallel grooves or lines, such as glacial stria.


a. A line or furrow generally seen on the walls of a lode or fault.

b. Plural of stria.


Adj. of striation.

striated cleavage

A cleavage surface grooved with striae, e.g., plagioclase.

striated crystal

A crystal face grooved with striae; e.g., pyrite or quartz.


a. See: stria.

b. One of multiple scratches or minute lines, generally parallel, inscribed on a rock surface by a geologic agent, i.e., glaciers, streams, or faulting. Syn: scratch. CF: slickensides. c. The condition of being striated; the disposition of striations.--Adj: striated; striate.

striding level

a. A spirit level so mounted that it can be placed astride a surveying instrument and so supported that it can be used for precise leveling of the horizontal axis of the instrument or for measuring any remaining inclination of the horizontal axis.

b. A demountable spirit level that can be attached to the telescope tube to level the line of sight.


a. The course or bearing of the outcrop of an inclined bed, vein, or fault plane on a level surface; the direction of a horizontal line perpendicular to the direction of the dip. CF: direction of strata; trace; trend.

b. v. To find a vein of ore. n. A valuable discovery. c. See: course; level course; fault strike. d. To withdraw supports. See also: line of bearing. Syn: strike a lead.

strike a lead

See: strike.

strike cut

In separating blocks of stone in a quarry, the cut that is parallel to the strike of the rock strata.

strike fault

A fault whose strike is parallel to the strike of the strata. CF: dip fault; oblique fault.

strike shift

In a fault, the shift or relative displacement of the rock units parallel to the strike of the fault, but outside the fault zone itself; a partial syn. of strike slip. See also: shift.

strike-shift fault

See: strike-slip fault.

strike slip

a. In a fault, the component of the movement or slip that is parallel to the strike of the fault. CF: dip slip; oblique slip. Syn: horizontal displacement; horizontal separation. Partial syn: strike shift.

b. A horizontal component of the slip parallel with the fault strike.

strike-slip fault

a. A fault on which the movement is parallel to the fault's strike. CF: dip-slip fault. See also: transcurrent fault. Syn: strike-shift fault.

b. A fault in which the net slip is practically in the direction of the fault strike. Syn: transcurrent fault.

strike valley

A valley eroded in and parallel to the strike of the underlying rocks of a region. Syn: longitudinal valley.

strike working

Where the dip of the coal seam is about 1 in 10 or less, the opencast method of working usually employed is to excavate along lines parallel to the outcrop. This is termed the strike or opencast method. See also: box-cut method.


Electrodepositing, under special conditions, a very thin film of metal that will facilitate further plating with another metal or with the same metal under different conditions.

striking hammer

A quarryman's hammer for striking a rock drill.

striking plates

Two horizontal timbers separated by striking wedges and supporting an arch center. The latter is lowered by slacking the wedges.

striking solution

A dilute solution of silver cyanide, containing potassium cyanide, in which articles to be silver-plated are dipped before being immersed in the silver bath proper.


a. Drilling bit, jars, drill stem, rope socket, and other tools connected to the lower end of a drilling cable in standard or percussion drilling. Also used for the rig and complete drilling equipment. Syn: drill string; string of tools.

b. A measurement of depth of a drill hole obtained by stringing over the length of cable from the drilling floor to the crown pulley on top of the derrick or mast. c. A very small vein, either independent or occurring as a branch of a larger vein; a stringer.


a. A mineral veinlet or filament, usually one of a number, occurring in a discontinuous subparallel pattern in host rock. See also: stringer lode.

b. A thin layer of coal at the top of a bed, separating in places from the main coal by material similar to that comprising the roof. c. A heavy timber or plank, usually horizontal but sometimes inclined, supporting other members of a structure; also, the horizontal crosspiece in square set timbering. d. See: roof stringer.

stringer lead

A small orebody--generally, a vein leading to a more valuable one.

stringer lode

A shattered zone containing a network of small nonpersistent veins. Syn: stringer zone. See also: stringer.

stringer sets

Mine timbering in which the caps reach across two or more sets in a drift or stope.

stringer zone

See: stringer lode.

string loading

Filling a drill hole with cartridges smaller in diameter than the hole, without slitting or tamping them.

string of tools

a. In a churn drill, the tools suspended on the drilling cable.

b. The entire downhole drilling assembly. See also: string.

string survey

a. A rough method of transferring points from upper to lower levels in very narrow steep workings by suspending strings from point to point and measuring offsets. The excavation dimensions may be similarly obtained. See also: plumbing.

b. The use of stretched strings in awkward underground workings to provide survey lines and a basis for offsets. In the lost-thread method of survey, a string or thread is paid out over a measuring device as a traverse line is walked.


a. In mining, to remove the earth, rock, and other material from the mineral to be mined, usually by power shovels. Generally practiced only where the mineral lies close to the Earth's surface.

b. To remove from a quarry, or other open working, the overlying earth and disintegrated or barren surface rock. See also: baring. c. To mine coal, alongside a fault, or barrier. d. To fill prepared coal from a coal face. See: stripping. Syn: stripping a mine.

Stripa process

a. A heavy medium process developed in Sweden for concentrating iron, copper, and chromite ores. The rate of supply of water over a shaking bed of wet sand effects the separation of heavy and light fractions.

b. A method of gravity treatment of coarse sands, in which feed is shaken along horizontal launder and at the same time kept in teeter by hydraulic water. Constituent minerals stratify into separable layers.

strip-borer drill

A skid- or crawler-mounted drill operated by electric motor or diesel engine. It is used at quarry or opencast sites for drilling horizontal blast holes 3 to 6 in (7.6 to 15.2 cm) in diameter, and up to 100 ft (30 m) in length, without the use of flush water. It cannot penetrate strong strata.


The series of bands of variation in color or texture in a rock mass, or the course of the planes of such bands, as indicative of the course of the bedding plane when that is otherwise obscure. See also: ribbon.


Trademark for a dynamite for coal stripping operations.

strip mine

A stripping; an opencut mine in which the overburden is removed from a coalbed before the coal is taken out. See also: opencast; opencut; openpit mine.

strip mining

The mining of coal by surface mining methods as distinguished from the mining of metalliferous ores by surface mining methods; the latter is commonly designated as openpit mining. See also: opencast method; openpit mining; surface mining.

strip packing

An arrangement of alternate packs and wastes built in a direction parallel to the gate roads in longwall conveyor mining. A common practice is to allow 5-yd (4.5-m) wastes between 4-yd (3.7-m) packs, or both are made 5 yd wide. The dimensions vary with local conditions. See also: stowing method; double packing; single packing.

stripped illite

See: degraded illite.

stripped plain

A plain composed of flat-lying or gently tilted sedimentary rocks from which sediments have been removed down to some resistant bed that has controlled the depth of erosion. CF: dip slope.


a. A nearly depleted well whose income barely exceeds operating cost of production.

b. In the quarry industry, a laborer who cleans up dirt left by the power shovel in stripping overlying ground from rock, using a shovel and wheelbarrow.


a. The removal of earth or nonore rock materials as required to gain access to the desired coal, ore, or mineral materials; the process of removing overburden or waste material in a surface mining operation.

b. The earth, rock, or soil so removed. c. The loading or clearing away of coal from a longwall face after shotfiring. d. Opencast mining. e. See: stripping the quarry; strip. f. In chemical extraction of minerals, treatment of pregnant solution to remove dissolved values.

stripping a gutter

Removing the headings from off the wash dirt, which is left undisturbed.

stripping a jig

Aust. The forming of a jig, by enlarging a cut-through on an incline. See also: jig.

stripping a mine

a. See: strip.

b. Robbing a mine of its best ore.

stripping area

In stripping operations, an area encompassing the pay material, its bottom depth, the thickness of the layer of waste, the slope of the natural ground surface, and the steepness of the safe slope of cuts.

stripping a shaft

a. Taking out the timber from an abandoned shaft.

b. Trimming or squaring the sides of a shaft.

stripping-pit limits

The strip area that includes area of pay material plus enough area beyond the limits of the ore pit to provide for a bench. The total volume of stripping will be that vertically above the limits of the ore pit plus that outside of the ore pit necessary to maintain safe strip-pit slopes and benches and provide working approaches to the pit.

stripping ratio

The unit amount of spoil or overburden that must be removed to gain access to a unit amount of ore or mineral material, generally expressed in cubic yards of overburden to raw tons of mineral material.

stripping salt

See: abraumsalze.

stripping shovel

A shovel with an esp. long boom and stick that enables it to reach further and pile higher.

stripping-shovel operator

In bituminous coal mining, one who operates a power shovel in a strip mine to strip back overlying ground and to load coal into cars. Also called coal-loading-shovel engineer; loading-shovel engineer. Syn: boom cat.

stripping solution

In solvent extraction, the aqueous solution used to re-extract the metal from the pregnant solution.

stripping system

The removal of the overburden and mining of the ore in one or more benches, the ore face being broken by blasting and the broken ore loaded by hand, shoveling machine, or steam shovel. The name "terrace or bench open-pit working" has been suggested.

stripping the quarry

The removal of all dirt and unwanted disintegrated material from the quarry face. See: stripping.

strip pit

A coal or other mine worked by stripping. An open-pit mine.

strip sample

A sample, making a notch or groove, cut from roof to floor of a coal seam, or from hanging wall to footwall of a vein. See also: channel sample.

strip thrust

See: decollement.


a. The distance traveled by a piston in a pump or a piston in a hydraulic-feed mechanism on a drill.

b. The maximum distance a piston moves within a cylinder before the direction of its travel is reversed. c. The distance a churn-drill stem and bit are raised for dropping while drilling.

stroke of crusher

The difference between the open and closed positions measured at the throat of the crusher. For small crushers it is about 3/8 to 3/4 in (0.95 to 1.9 cm), and for large crushers from 1 to 2 in (2.5 to 5 cm). Also called throw of crusher.


A type of mixed rock or chorismite in which the units of the fabric (granitic material and metamorphic or sedimentary rock) form a system of layers, strata, or bands so intricately united that the whole rather than the individual layers constitutes the geological field unit.


A structure produced by sediment trapping and/or precipitation as a result of the growth of cyanophytes (blue-green algae). It has a variety of gross forms, from nearly horizontal to markedly columnar, domal, or subspherical. Syn: algal stromatolite; stromatolith.


a. See: stromatolite.

b. A complex, sill-like igneous intrusion that is interfingered with sedimentary strata.


An orthorhombic mineral, AgCuS ; metallic; soft; steel gray with blue tarnish; sp gr, 6.2 to 6.3; in copper-silver veins; a source of copper and silver. Syn: silver-copper glance.


a. Hard and thick; said of dikes.

b. Important or rich; said of veins. c. Referring to the character of bind, meaning that the argillaceous material is largely mixed with the arenaceous or siliceous material. d. Scot. Hard, not easily broken, e.g., strong coal, strong blaes. e. Said of large or important mineral veins or faults.


A heavy timber or metal beam or bar for taking a strain.

strong lode

A large, persistent lode. At Alston moor, England, applied to lodes lying in a fault plane in which the difference of level between similar strata is considerable.


An orthorhombic mineral, 4[SrCO (sub 3) ] ; aragonite group; in hydrothermal veins associated with limestones, less commonly with eruptive rocks in California, New York, Washington, Germany, and Mexico; a source of strontium. Syn: carbonate of strontium.


A monoclinic mineral, (Sr,Ca) (sub 2) B (sub 14) O (sub 23) .8H (sub 2) O; forms a series with ginorite. CF: ginorite.


A silvery-white, alkaline-earth metal. Symbol, Sr. It does not occur naturally; found chiefly as celestite (SrSO (sub 4) ) and strontianite (SrCO (sub 3) ). Major use at present is for color television picture tubes.


A hexagonal mineral, Sr (sub 5) (PO (sub 4) ) (sub 3) (OH) ; apatite group; vitreous; light green; in sugary albite filling interstices between crystals of aegirine and eckermannite in veins in alkalic pegmatites from Inagil massif, southern Yakutia, Russia.

strontium minerals

Used primarily in television face-plate glass, in ceramic ferrites, and in pyrotechnics. The United States imports most of its celestite, the chief source of strontium, from Mexico and Germany.

strontium stannate

SrSnO (sub 3) ; sometimes used as an additive to titanate bodies, one result being a decrease in the Curie temperature.

strontium titanate

SrTiO (sub 3) ; isometric; and melting point, 1,670 degrees C. Used in ceramic dielectric bodies, either alone or in combination with barium titanate or other titanates.

strontium zirconate

SrZrO (sub 3) ; melting point, 2,700 degrees C; sp gr, 5.48. Sometimes used in small amounts (3% to 5%) in ceramic dielectric bodies, one effect being to lower the Curie temperature.

struck capacity

a. The capacity of a mine car, tram, hoppit, or wagon to the flat surface at the edges; i.e., the volume of water it would hold if of watertight construction.

b. In scraper loading, the maximum volume of liquid that the bowl can hold. CF: heaped capacity.

struck out

Corn. The termination of a vein or lode by a fault.


Of or pertaining to rock deformation or to features that result from it.

structural analysis

The initial stage of structural design, in which all the forces carried by the various parts of a structure are determined.

structural basin

A low area in the Earth's crust, of tectonic origin, in which sediments have accumulated, e.g., a circular centrocline such as the Michigan Basin, a fault-bordered intermontane feature such as the Bighorn Basin of Wyoming, or a linear crustal downwarp such as the Appalachian Basin. Such features were drainage basins at the time of sedimentation, but are not necessarily so today.

structural bottoming

See: bottoming.

structural color

See: pseudochromatism.

structural control

The influence of structural features on ore deposition, e.g., ore minerals filling fractures. CF: stratigraphic control.

structural dome

See: dome.

structural drilling

Drilling done specif. to obtain detailed information delineating the location of folds, domes, faults, and other subsurface structural features undiscernible by studying strata exposed at the surface. CF: structure drilling.

structural fabric

See: fabric.

structural geology

The branch of geology that deals with the form, arrangement, and internal structure of the rocks, and esp. with the description, representation, and analysis of structures, chiefly on a moderate to small scale. The subject is similar to tectonics, but the latter is generally used for the broader regional or historical phases.

structural high

High point of a structure. See also: high.

structural load

The load due to the structure itself as distinguished from the imposed load.

structural log

A record of the breaks, fractures, faults, and physical properties of rocks within a formation.

structural low

Low point of a structure. See also: low.

structural petrology

The analysis of fabric on the thin-section or micro scale. It includes the study of grain shapes and relationships (microstructure) and the study of crystallographic preferred orientations. The transmission electron microscope is also employed to examine the substructures of deformed crystals.

structural plain

See: stripped plain.

structural relief

a. The vertical distance between stratigraphically equivalent points at the crest of an anticline and in the trough of an adjacent syncline.

b. More generally, the difference in elevation between the highest and lowest points of a bed or stratigraphic horizon in a given region.

structural steelwork

Rolled steel sections or other fabricated members assembled to form structural frames by riveting, welding, bolting, or a combination of all three.

structural terrace

a. A local shelf or steplike flattening in otherwise uniformly dipping strata, composed of a synclinal bend above and an anticlinal bend at a lower level.

b. A terracelike landform controlled by the structure of the underlying rocks; esp. a terrace produced by the more rapid erosion of weaker strata lying on more resistant rocks in a formation with horizontal bedding.

structural valley

A valley that owes its origin or form to the underlying geologic structure.

structural vitrain

See: phyllovitrinite.


a. The parts or members of any building that carry the loads and transmit them to the foundations. Structures in mining areas may suffer some subsidence and are designed accordingly.

b. Geologically, the disposition of the rock formations; i.e., the broad dips, folds, faults, and unconformities at depth. c. In petrology, one of the larger features of a rock mass, like bedding, flow banding, jointing, cleavage, and brecciation; also, the sum total of such features. CF: texture. d. See: soil structure.

structure contour

A contour that portrays a structural surface such as a formation boundary or a fault. Syn: subsurface contour. CF: contour.

structure-controlled shoot

An ore shoot that is localized by geologic structure. Changes in strike and dip of fissures are favorable sites for ore shoots.

structure drilling

a. Exploratory drilling to determine the geological structure with reference to the coal or minerals sought. Rotary or diamond drilling is usually employed to yield cores at key horizons.

b. A form of drilling practiced in the Lake Superior iron district to sample soft iron formations by countercirculation-wash boring methods. CF: structural drilling.

structure section

A diagram to show the observed geological structure on a vertical face or, more commonly, to show the inferred geological structure as it would appear on the side of a vertical trench cut into the earth. The vertical scale is often exaggerated.

structure test hole

A hole drilled for geologic structure alone, although other types of information may be acquired during the drilling. This type of hole is drilled to a structural datum, which is normally short of known or expected producing zones. See also: seismic shothole; slim hole.


A triclinic mineral, MnFe (sub 2) (PO (sub 4) ) (sub 2) (OH) (sub 2) .6H (sub 2) O ; pseudomonoclinic; forms straw-yellow radiating fibers from the alteration of triphylite.


a. A piece of wood or steel inserted between each pair of steel or timber supports on roadways to resist buckling and to maintain the proper spacing between the sets.

b. A mine prop to sustain compression, whether vertical or inclined. c. An inside brace. d. A diagonal brace between two legs of a drill tripod or derrick; also, a vertical-compression member in a structure or in an underground timber set.

strut tenon

A tenon, such as is used on a diagonal piece or strut, usually on heavy timbers.

Struve ventilator

A pneumatic ventilating apparatus consisting of two vessellike gas holders, which are moved up and down in a tank of water. By this means, air is sucked out of a mine.


An orthorhombic mineral, (NH (sub 4) )MgPO (sub 4) .6H (sub 2) O ; soft; has one perfect and one good cleavage.

stub entry

A short, narrow entry turned from another entry and driven into the solid coal, but not connected with other mine workings; a dead end. Syn: dead end.

Stub's gage

A gage for measuring the size of wire. Also known as Birmingham gage.

stub switches

Switches used to some extent on narrow-gage industrial tramways; consisting of a pair of short switch rails, held only at or near one end and free to move at the other end to meet rails of straight or diverging track.


a. A bolt having one end firmly anchored.

b. A threaded rod or a bolt without a head. c. An upright beam or scantling as in the framework of a dwelling.


a. A strong crossbeam in a shaft collar set.

b. Corn. A prop to support the middle of a stull. c. A distance piece between successive frames of timbering. d. A vertical member of a shaft-timber set. The sets are placed at each corner and at the intersection of the dividers and the wallplates. e. An upright prop supporting a platform in a mine, usually one of a set of four.

stud-type chain

A roller chain in which the inner (block) links are connected solidly by nonrotating bushings.


a. A mineral having foreign ions in large interstices in its structure; e.g., garnet with an extra cation.

b. A mineral structure derived from another by coupled replacement of a cation with two cations of lower valence, one of which occupies a structural cavity; e.g., feldspars derived from coesite by aluminum ions replacing silicon in the framework coupled with alkali or alkali earth ions in structural cavities.

stuffed mineral

A mineral having large interstices in its structure may accommodate various foreign ions in these holes; such a mineral is then said to be stuffed. The stuffing may have considerable consequences on the stability of the mineral.

stuffing box

A chamber designed to contain packing and to maintain a fluid-tight joint about a piston rod where it enters a cylinder or around a drill rod where it enters the casing at the collar of a borehole.


a. A timber prop set between the walls of a stope, or supporting the mine roof.

b. A timber platform on which valueless rock or mineral is deposited. c. Corn. A platform (stull-covering) laid on timbers (stullpieces), braced across a working from side to side, to support workers or to carry ore or waste. d. A round timber used to support the sides or back working of a mine.

stull covering

A platform resting on stulls in a stope as a stage for miners or for holding rock or mineral.

stulled stopes

Stopes in which the roof is supported by stulls, square-set timbering, or concrete columns.

stull piece

A piece of timber placed slanting over the back of a level to prevent rock falling into the level from the stopes above.

stull stoping

The walls of narrow veins frequently are supported by stull timbers placed between the foot and hanging walls, which constitute the only artificial support provided during the excavation of the stopes. Stulls may be placed at irregular intervals to support local patches of insecure ground, in which case the stopes are virtually open stopes. Sometimes the stulls are placed at regular intervals both along the stope and vertically, in which case stull stoping should be considered a distinctive method.

stull timbering

The support of walls in shrinkage stoping by setting stulls.


An approx. horizontal passageway into a mine; an adit. Taken from the German term stollen.


a. Entry pillars; small portion of room pillars left for pick mining.

b. A small pillar of coal left between the gangway or airway and the breasts to protect these passages; any small pillar. c. A narrow pillar of coal.


A narrow heavy dozer attachment used in pushing out stumps.

stump prop

Short posts set under the crown bars of a tunnel.

stump pulling

See: pillar robbing.


A quarry worker's term for the formation of fractures caused by the cutting bars of a channeling machine striking the rock with excessively heavy blows.

Sturtevant balanced rolls

Rolls in which all four boxes are moveable in position by springs to divide the thrust whenever the springs yield and thus reduce internal stresses.

Sturtevant grinder

A disk grinder in which one disk is stationary and the other rotates. The stationary disk is moved out of center from time to time, so that any groove that forms can be ground out.

Sturtevant ring roll crusher

A crusher similar to the Kent roller mill.

Sturtevant roll jaw crusher

A crusher in which the motion of the upper part of the jaws is like that of the Dodge crusher, while the lower parts of the jaws, of cylindrical surfaces of varying radii, grind the ore between them.

Sturzelberger iron reduction process

A process evolved for dealing with pyrite roasting residues rich in zinc (8% to 10%). The direct reduction takes place in a short rotary drum that has a rammed tar-dolomite lining. Lime is added to produce a highly basic slag; the pyrite cinders, precalcined, are mixed with coke breeze and fired with pulverized coal burners. The zinc is recovered from the waste gases. The drum works discontinuously in 7-h heats, and the capacity of such a plant is limited in comparison with a blast furnace. The product is a liquid pig iron.

Stygian deposits

A general term for ore deposits formed underground by waters of atmospheric origin.


A surface or contact, usually in carbonate rocks, that is marked by an irregular and interlocking penetration of the two sides: the columns, pits, and teethlike projections on one side fit into their counterparts on the other. As usually seen in cross section, it resembles a suture or the tracing of a stylus. The seam is characterized by a concentration of insoluble constituents of the rock; e.g., clay, carbon or iron oxides, and is commonly parallel to the bedding. Etymol: Greek stylos, pillar, + lithos, stone. Syn: crowfoot; suture joint.


Syn: tetrahedrite. Formerly applied to tetrahedrite containing appreciable silver.

Styrian jade

Pseudophite, a compact massive variety of clinochlore.


a. Gr. Brit. Carbonic acid gas, often found in old workings and given off in most shallow mines. Also spelled stithe.

b. See: blackdamp.