Appendix:Dictionary of Mining, Mineral, and Related Terms/S/10

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square

A term used in the slate industry with reference to roofing slate. A square is a sufficient number of any size to lay 100 ft (super 2) (9.29 m (super 2) ) of roof, allowing the standard 3-in (7.62-cm) lap. The estimated weight of a square of 1/4-in (6.4-mm) slate is 1,000 lb (454 kg).

square drill collar

A long stabilizer of rectangular shape that when used properly gives a super-packed-hole effect. Square drill collars are made primarily from 30-ft (9.14-m) steel bar stock with a diagonal measurement greater than the hole diameter in which the collar will eventually be used. This collar has proved successful in controlling rapid directional and deviational changes in wells drilled in a disturbed-belt-type area.

square-mile-foot

A unit of measure representing the volume of water 1 ft (0.3 m) deep over an area of 1 mile (super 2) (2.6 km (super 2) ). See also: acre-foot.

square set

A set of timbers used to provide support in a stope or an underground mine. Each timber set consists of a vertical post and two horizontal members known as a cap and girt. The timber ends are sawed to allow adjoining timbers to interlock. They are framed at mutual right angles, and when joined with other sets form a continuous timber framework that conforms to the irregular shape of the stope. The posts are 6 to 7 ft (1.83 to 2.13 m) high, while the caps and girts are 4 to 6 ft (1.22 to 1.83 m) long. Caps and girts are placed on top of the posts, a line of caps being at right angles to a line of girts. Square sets vary in dimensions at different mines, but in general should give a clear opening of at least 5 ft (1.52 m) each way between posts to afford sufficient working space in the stope, and a clear height of 6-1/2 ft (1.98 m) is about the minimum height desirable. This system of timber support can be adapted to large and irregular orebodies resulting in an elaborate network extending the full height and width of a stope.

square-set and fill

See: square-set stoping.

square-set block caving

A method of block caving in which the caved ore is extracted through drifts supported by square sets. A retreating system is adopted.

square-set slicing

See: top slicing and cover caving.

square-set stoping

A method of stoping in which the walls and back of the excavation are supported by a system of interlocking framed timbers (square set). A square set of timber consists of a vertical post and two horizontal members set at mutually right angles. The mining process is slow and only enough ore is excavated to provide room for installation of each successive set of timber. The stopes are usually mined out in floors or horizontal panels, and the sets of each successive floor are framed into the top of the preceding floor. Syn: alternate pillar and stope; overhand vertical slice; underhand vertical slice. CF: back-filling system.

square-set system

A method of mine timbering in which heavy timbers are framed together in rectangular sets, 6 to 7 ft (1.83 to 2.13 m) high, and 4 to 6 ft (1.22 to 1.83 m) square, so as to fill in as the orebody is removed by overhand stoping.

square-set underhand

See: square-set stoping.

square thread

a. A screw thread the cross section of which is square.

b. A robust type of screw thread that can transmit thrust in both directions.

square work

See: sublevel stoping.

square work and caving

See: sublevel stoping.

squat lads!

Fall flat down on the floor. In the early days of coal mining, igniting the gas was a very common thing; so, whenever an explosion took place, the colliers shouted to one another, "Squat, lads!"

squealer

A shot that breaks the coal only enough to allow the gases of detonation to escape with a whistling or squealing sound; also called a whistler.

squeal-out

Arkansas. See: seam-out; squealer.

squealy coal

Arkansas. Seamy coal from which the powder gases escape with a squealing sound.

squeeze

a. A crushing of coal or other materials with the roof moving nearer to the floor, due to the weight of the overlying strata.

b. The settling, without breaking, of a mine roof over a considerable area of workings. Also called creep; crush; pinch; nip. c. The effect of the closure of stope walls on supports placed between them. d. A passageway in a cave that is very narrow and can be passed by a person only with great difficulty. e. Applied to sections in coal seams where they have become constricted by the squeezing in of the overlying or underlying rock as a result of pressure during folding or other movements. f. A pinch of a vein in passing through hard bands of rock. g. To inject a grout into a borehole under high pressure. h. The plastic movement of a soft rock in the walls of a borehole or mine working that reduces the diameter of the opening. i. Pumping cement back of casing under high pressure to block off or re-cement channeled areas. j. The rapid or gradual closing of a mine working by the displacement of weak floor strata from beneath supporting pillars into adjacent mine rooms. See also: want.

squeezer

A mine tub controller that acts by squeezing the tub or the wheels.

squeeze riveter

A single-stroke, compressed-air cylinder for closing rivets through the medium of a toggle mechanism.

squeezing

The slow increase in weight on pillars or solid coal eventually resulting in such things as crushing of the coal, heaving of the bottom, and the driving of pillars into soft floor or top. The cause normally is leaving pillars or other supports which, after considerable area is opened up, prove to be inadequate, permitting the top to settle gradually with transfer of the weight to active places and solid coal.

squib

a. See: electric squib.

b. A thin tube filled with black powder, forming a slow-burning fuse to explode a stemmed charge of black powder. c. A small charge of powder exploded in the bottom of a drill hole, to spring the rock, after which a heavy shot is fired. A springing shot. d. In well boring, a vessel, containing the explosive and fitted with a time fuse, that is lowered into a well to detonate the nitroglycerin charge. e. A firing device that will burn with a flash which will ignite black powder.

squib shot

A blast with a small quantity of high explosives fired at some point in a borehole for the purpose of dislodging some foreign material that has fallen into it.

squinted vein

Derb. A mineral vein cut by a dike and thereby thrown out of alinement on the two sides of the dike.

squirrel cage fan

A centrifugal blower with forward-curved blades.

squirrel-cage motor

An alternating current electric motor with many applications. The rotor is made of strong parallel copper or aluminum bars on the perimeter, joined to end rings of the same metal.

squotting

A stage in the heating of clay when so much of the material has fused that the mass begins to lose its shape and becomes viscous. See also: fusion of clay; vitrifying.

stab

a. To guide a pipe, casing, or drill rod so that the threads will engage properly.

b. To recover a drill tool lost in a borehole by using a spear-shaped or pointed fishing tool. c. In adding to a drill string, the action of lining up and catching the threads of the loose piece.

stability

a. The resistance of a structure, slope, or embankment to failure by sliding or collapsing under normal conditions for which it was designed; e.g., bank stability and slope stability. See also: bank slope stability.

b. In thermodynamics, an equilibrium state to which a system will tend to move from any other state under the same external conditions.

stability series

A grouping of minerals arranged according to their persistence in nature; i.e., to their resistance to alteration or destruction by weathering, abrasion during transportation, and postdepositional solution; e.g., olivine (least stable), augite, hornblende, biotite (most stable). The most stable minerals are those that tend to be at equilibrium at the Earth's surface. Syn: order of persistence.

stabilized coupling

A rod coupling built up to reaming-shell size by welding on an abrasion-resistant metal, applied in ridges parallel to the long axis of the drill rod.

stabilized tray conveyor

See: over-and-under conveyor.

stabilizer

a. A hardened, splined bushing, sometimes freely rotating, slightly larger than the outer diameter of a core barrel. Also called ferrule; fluted coupling.

b. A misnomer for guide rod. c. Any powdered or liquid additive used as an agent in soil stabilization. See also: processing.

stable

a. Not readily decomposed or deformed. CF: unstable.

b. A short drivage, room, or space excavated at the end of a longwall face to accommodate a coal cutter or cutter loader. The stable provides room for turning the machine where this is necessary, and also exposes a buttock for the machine to start its cut across the face.

stable gravimeter

An instrument that uses a high order of optical and/or mechanical magnification so that an extremely small change in the position of a weight or associated property can be accurately measured.

stable hole conveyor

A short belt or other conveyor for use in stables in advance of the longwall face. The conveyor is usually about 18 in (46 cm) wide and driven at the tail end by a combined electric motor and drive pulley. The unit can be transported by sliding on steel skids, and is useful where coal or stone has to be moved short distances in confined spaces. See also: shortwall.

stable isotope

A nuclide that does not undergo radioactive decay.

stable lead

Any of the nonradioactive isotopes of lead.

stable relict

A relict mineral that was not only stable under the conditions prevailing while it was formed but also under newly imposed conditions of metamorphism. CF: unstable relict.

stack

a. To stand and rack drill rods in a drill tripod or derrick.

b. Chock; a chock built of old timber. c. A shaft furnace. d. Any structrue or part thereof that contains a flue or flues for the discharge of gases. See also: inwall.

stack effect

The impulse of a heated gas to rise in a vertical passage, as in a chimney, a small enclosure, or building. Syn: chimney effect.

stacker

a. A conveyor, mounted on a long steel boom, for carrying tailings beyond the stern of a gold or tin dredge to avoid silting it up.

b. A machine for blending ore before processing. c. A conveyor adapted to piling or stacking bulk materials, packages, or objects. d. With a blending system, the stacker operates over the stocking conveyor in a manner similar to a wing belt tripper to build layered piles or beds of material parallel to the stocking conveyor. See also: boom conveyor; portable conveyor; wing belt tripper; apron conveyor; belt conveyor; flight conveyor; portable conveyor. e. One who controls conveyor belt moving molds containing molten lead through water spray to stamping and discharge tables. f. One who stacks coal, etc. g. Leic. A miner who looked after the unloading of the coal on the bank, on behalf of the miners, in the earlier days of mining. h. A machine for blending ore that beds the ore before reclaiming for processing.

stack height

The height of a convector enclosure measured from the bottom of the enclosure to the top of the outlet.

stacking fault

A type of "plane defect" in a crystal structure, caused by one or more closest-packed layers added to or removed from a normal cubic closest-, hexagonal closest-, or other regular closest-packed sequence.

stadia

a. A surveying technique or method using a stadia rod in which distances from an instrument to the rod are measured by observing through a telescope the intercept on the rod subtending a small known angle at the point of observation, the distance to the rod being proportional to the rod intercept. The angle is usually defined by two fixed lines in the reticle of the telescope.

b. See: stadia rod. c. An instrument used in a stadia survey; esp. an instrument with stadia hairs.---Pl: stadias. The term is also used as an adj. in such expressions as stadia surveying, stadia distance, and stadia station.

stadia hairs

Horizontal cross hairs equidistant from the central horizontal cross hair; esp. two horizontal parallel lines or marks in the reticle of a transit telescope, arranged symmetrically above and below the line of sight, and used in the stadia method of surveying. Syn: stadia wires.

stadia rod

A graduated rod used with an instrument having stadia hairs to measure the distance from the observation point to the place where the rod is positioned. Syn: stadia. See also: telemeter rod.

stadia surveying

The process of measuring distances and elevations by observing through a telescope the distance intercepted on a rod between two horizontal cross-hairs. These hairs are carried on the same ring as the regular horizontal crosshair, and are equidistant from it.

stadia tables

Mathematical tables from which may be found, without computation, the horizontal and vertical components of a reading made with a transit and stadia rod.

stadia wires

See: stadia hairs.

stadia work

Tacheometric survey, in which points sighted from a survey station are oriented as with a theodolite, and their distance is read by means of a vertically held leveling staff on stadia wires.

staff

a. A surveyor's leveling rod.

b. An iron puddler's rabble or rabbler.

staff gage

Graduated scale marked on a rod or a metal plate, or on the masonry of a bridge pier or similar structure, from which the depth of water in a canal, dock, or river can be read.

staff hole

A small hole in a puddling furnace through which the puddler heats the staff. See also: staff.

staff man

The person who carries a leveling staff for a surveyor. See also: target rod; telemeter rod.

Staffordian Series

The so-called transition group of the British Coal Measures, between the Middle and Upper Coal Measures in the Carboniferous System. They include the Newcastle-under-Lyme Group and the Etruria Marl, and the Blackband Group in north Staffordshire, England.

staflux

A material made by sintering together lumps of limestone and certain kinds of iron oxide, such as iron ore or mill scale, at a temperature of 1,450 degrees C in a rotary furnace. Though fusion does not occur, the iron oxide rapidly penetrates the limestone completely and forms dicalcium ferrite.

stage

a. A landing, such as in a shaft mine.

b. A platform on which mine cars stand. c. A step in a process. d. A time-stratigraphic unit next in rank below a series and corresponding to an age; it generally consists of several biostratigraphic zones. It is the most important unit for long-range correlation.

stage addition

In flotation, this refers to deliberate use of insufficient reagent in the early part of the treatment to increase selectivity of conditioning, followed by further addition at a later point in the process.

stage compression

See: compound compression.

stage crushing

A method of crushing in which there is a series of crushers, each one crushing finer than the one preceding.

stage grinding

Comminution in successive stages.

stage loader

See: feeder conveyor.

stage plumbing

A precise method of orienting underground workings in which plumblines are transferred down a deep shaft in stages of 400 to 600 ft (120 to 185 m). While shaft sinking is in progress, the lines can also be employed to orient the shaft itself and to keep it plumb.

stage pumping

Draining a mine by means of two or more pumps placed at different levels, each of which raises the water to the next pump above or to the surface.

stage treatment

In mineral processing, development of the desired condition of the particles by defined states, such as comminution to successively fine sizes (possibly coupled with staged concentration or gangue elimination) between such stages of communition.

stage winding

Winding, usually in compound shafts, where the wind is divided into two or more stages, and underground winding engines are installed to deal with the lower stages.

stage working

A system of working minerals by removing the strata above the beds, after which the various beds are removed in steps or stages.

staggered blastholes

When shot firing in thick coal seams, two rows of holes may be necessary. These are usually staggered to a triangular pattern to distribute the burden. A similar pattern is often adopted in quarry wellhole blasting.

staggered holes

To arrange boreholes in a row, in such a manner that those in one row are placed opposite the spaces between the boreholes in the next row.

stag hole

Usually a short hole drilled, charged, and fired to shatter the rock near the collars of the cut holes.

staging

a. A temporary flooring or scaffold, or platform.

b. One or more working platforms, fixed at defined levels in deep trenches or similar excavations, on to which excavated earth is thrown by shovel.

stained stone

A gemstone with color altered by a coloring agent, such as a dye, or by impregnation with a substance, such as sugar, followed by chemical or heat treatment, which usually produces a permanent color; e.g., green chalcedony. CF: burnt stone. See also: altered stone; heated stone.

stainierite

See: heterogenite.

stainless steel

Iron-base alloy containing enough chromium to confer a superior corrosion resistance.

stains

Inclusions and intergrowths in mica arising from foreign materials, resulting in a partial or total loss of transparency.

stake

a. Grubstake.

b. A pointed piece of wood driven into the ground to mark a boundary, survey station, or elevation. c. See: sprag. d. An iron peg used as power electrode to transfer current into the ground in electrical prospecting. This term is also used to include all power and search electrodes, such as iron pegs, copper coils, and copper screens; also, a station marker used by field parties. e. A permanent interest, as in an enterprise or a mine.

staking out

The physical act of locating a lode or placer mining claim.

stalactite

A conical or cylindrical mineral deposit that hangs from the ceiling of a cave. See also: stalagmite. CF: helictite.

stalagmite

A conical or cylindrical mineral deposit that is developed upward from the floor of a cave by the action of dripping water. See also: stalactite. Syn: dropping stones. CF: helictite.

stalagmometer

An apparatus for determining surface tension. The mass of a drop of a liquid is measured by weighing a known number of drops or by counting the number of drops obtained from a given volume of the liquid.

stalch

Eng. A mass of ore left in a mine.

stall

a. A narrow coal drivage in pillar-and-stall. See also: narrow stall; stallman.

b. A working place at the coal face; a term associated with narrow workings.

stall-and-breast

See: room-and-pillar.

stall-and-room working

A pillar method of working a relatively thick coal seam by a system of compartments; a modification of pillar-and-stall.

stalling angle

The blades of axial-flow fans are of aerofoil section, which when inclined at a small angle (known as the angle of attack) to the air stream produce a large lift or raising force for a small drag or retarding force. The lift force is the useful one which gives the thrust to the air in an axial-flow fan. The lift increases with increase in the angle of attack until a point is reached when the lift begins to fall. This angle is the "critical" or "stalling angle." Syn: critical angle.

stallman

A collier who works at the face of a narrow stall or a longwall stall. The collier is paid according to a pricelist of so much per ton of coal loaded out and for other work, such as timbering. A stallman usually has another miner alongside.

stall roasting

The roasting of ore in small enclosures of earth or masonry walls. The enclosures are called stalls and may be open or closed.

stamler

See: feeder breaker.

stamp

a. To break up ore and gangue by machinery, for washing out heavier metallic particles.

b. A heavy pestle raised by water or steam power for crushing ore. A stamp in which the blow of the pestle is caused by its mere weight is called a gravity stamp.

stamp battery

See: stamp mill.

stamp duty

The amount of ore (tons) that one stamp will crush in 24 h.

stamper box

A stamp-mill mortar box.

stamp hammer

A power hammer that moves vertically.

stamp head

A heavy and nearly cylindrical cast-iron head fixed on the lower end of the stamp rod, shank, or lifter to give weight in stamping the ore. The lower surface of the stamp head is generally protected by a cheese-shaped shoe of harder iron or steel that may be removed when worn-out. These shoes work upon dies of the same form laid in the bottom of the mortar or stamper box. See also: stamp.

stamping

a. Reducing to the desired fineness in a stamp mill. The grain is usually not so fine as that produced by grinding in pans.

b. A general term covering almost all press operations. It includes blanking, shearing, hot or cold forming, drawing, bending, and coining. c. A process for application, by hand or by machine, of decoration to pottery ware; a rubber stamp with a sponge backing is used. Stamping is particularly suitable for the application of backstamps and for some forms of gold decoration. See also: backstamp.

stamping maundrill

Leic. A heavy pick.

stamp mill

An apparatus, and the building containing it, in which rock is crushed by descending pestles (stamps), operated by water power or steam power. Amalgamation is usually combined with crushing when gold or silver is the metal sought, but copper, tin, and other ores are stamped to prepare them for dressing. The technique is obsolete. Syn: stamp battery.

stamp shoe

The heavy, chilled-iron casting, attached to the lower end of a stamp piston, which does the actual crushing of rock in a stamp mill. It drops on a round steel block called a die.

stampsman

Person who attends or operates a stamp or stamp battery.

stampwork

A term used in the Lake Superior region for rock containing disseminated native copper.

stanchion

a. A vertical prop or strut.

b. A support or post of iron or wood.

stand

a. Two or more lengths of drill rod or casing coupled together and handled as a unit length as they are taken from a borehole and set upright in a drill tripod or derrick. See also: double; forble; treble.

b. A drill floor. c. To allow a cement slurry to remain undisturbed in a borehole until it hardens or sets. d. To set a string of casing in a borehole.

standage

a. Reservoir or storage capacity, said of water and of mine cars.

b. See: sump. c. The capacity of a sump or lodge. d. See: lodge.

standage room

A length of roadway provided near a shaft bottom to stock loaded mine cars and/or empty cars: (1) during peak hours when the coal reaches the pit bottom at a faster rate than the shaft can wind; and (2) during emergency periods, such as plant breakdown at the surface, thus permitting coal production to continue. In general, the standage room accommodates 45-min to 1-h winding capacity. See also: bunker conveyor; bunkering capacity.

standard air density

In mine ventilation, the standard density of air for mine ventilation work is considered to be 0.075 lb/ft (super 3) (1.2014 kg/m (super 3) ). This is based upon the weight of 1 ft (super 3) (0.028 m (super 3) ) of dry air at 70 degrees F (21.1 degrees C) at a sea-level pressure of 29.9 in (759 mm) of mercury.

standard bit

A bit the size and design of which are as specified in standards accepted by the drilling industry.

standard conditions

In refrigeration, an evaporation temperature of 5 degrees F (-15 degrees C), condensing temperature of 86 degrees F (30 degrees C), liquid temperature before the expansion valve of 77 degrees F (25 degrees C), and suction temperature 14 degrees F (-10 degrees C).

standard copper

Practically any brand of 96%, or higher, fineness.

standard core bit

See: standard bit.

standard electrode reference

Electrode used as a standard in measurements of electrode potential, because its potential is constant and reproducible; used for pH measurements, polarographic analysis, etc.

standard ignition test

A method developed for testing coal dust to obtain the limits of explosibility.

standard impinger

For many years, the Greenburg-Smith impinger was the routine dust sampling instrument in this country. It is still relied upon as a standard, but because of its size and weight, is little used underground today.

standard lay

See: regular lay.

standard mineral

See: normative mineral.

standard mix

Concrete mixed in the proportions of 1 part cement, 2 parts sand, and 4 parts coarse material. See also: aggregate; cement.

standard of ventilation

An adequate amount of ventilation to dilute and render harmless all noxious and flammable gases to such an extent that all roads and workings in a mine shall be kept in a fit state for working or passing therein.

standard parallel

a. A parallel of latitude that is selected as a standard axis on which to base a grid system; specif. one of a set of parallels of latitude (other than the base line) of the U.S. Public Land Survey system, passing through a selected township corner on a principal meridian, and on which standard township, section, and quarter-section corners are established. Standard parallels are usually at intervals of 24 miles north or south of the base line, and they are used to limit the convergence of range lines that intersect them from the south so that nominally square sections and townships can be laid out. Syn: correction line.

b. A parallel of latitude that is used as a control line in the computation of a map projection; e.g., the parallel of a normal-aspect conical projection along which the principal scale is preserved. c. A parallel of latitude on a map or chart along which the scale is as stated for that map or chart.

standard penetration test

a. A soil-sampling procedure to determine the number of blows by a drive hammer, freely falling a distance of 30 in (0.76 m) per blow, needed to drive a standard sampling spoon 1 ft (0.3 m). The first 6 to 7 in (15.24 to 17.78 cm) of penetration is disregarded, but the blows required to drive the sample the ensuing foot are counted.

b. See: penetration test.

standard plow

The original coal plow; a heavy double-ended machine with fixed blades. Its length is 6-1/2 ft (1.98 m); its height ranges from 14 to 31 in (35.6 to 78.7 cm). The depth of cut can be varied from 2 to 6 in (5.1 to 15.2 cm). The rapid plow has evolved from this relatively slow-moving machine.

standard pressure

a. A term applied to valves and fittings suitable for a working steam pressure of 125 psi (862 kPa).

b. See: normal pressure.

standard rig

a. An archaic term for a cable-tool drilling rig.

b. A common misnomer for cable-tool rig, churn-drill rig.

standard section

A geologic section showing as completely as possible a sequence of all the strata in a certain area, in their correct order, thus affording a standard for correlation. It supplements (and sometimes supplants) the type section, esp. for time-stratigraphic units.

Standard Temperature and Pressure

Atmospheric pressure of 760 mm of mercury, at 0 degrees C.

standard tin

Tin of 99.75% or greater purity.

standard wire gage

Gage number defining the diameter of wire. Abbrev.: SWG.

standby face

A spare conveyor face, of normal length, that could be worked should another face cease production due to faults, washouts, roof collapse, water, gas, or any other unforeseen impediment. Syn: spare face.

standdown

Gr. Brit. The sending of miners home because they cannot be usefully employed due to any reason outside the control of the management. In some cases, coal mining awards confine this right to certain occurrences, e.g., breakdown of plant or machines.

standing

a. Used by drillers to denote that work has been stopped for a considerable time.

b. Drill rods or casing stacked vertically in the drill tripod or derrick.

standing column

The column of drilling liquid left in the hole when the drill tools have been removed.

standing fire

A fire in a mine continuing to smoulder for a long time, often many years.

standing gas

A body of combustible gases known to exist in a mine, but not in circulation; sometimes fenced off.

standing shot

The result of a small or undercharged shot wherein the coal is loosened so that it is easily mined by pick. The term is a misnomer, as it applies to the result and not the "shot" or "charge."

standing time

Gr. Brit. The period when face workers are idle due to the lack of empty cars, etc. Payments are made to miners on piecework for time lost. See also: lying money.

stand of drill rods

See: stand.

standoff

a. A short length of core attached to and left standing upright in the bottom of the borehole when the core barrel is pulled.

b. On taper-tool or drillpipe joints, the space between the pin- and box-thread shoulders before wrenching up.

standpipe

a. A relatively short length of pipe driven into the upper soillike portion of the overburden as the first step of collaring or spudding-in a borehole. Also called conductor; conductor pipe.

b. A short piece of pipe wedged or cemented into a borehole after completion to act as a marker and keep collar free of cave. CF: surface string.

standpiping

Driving pipe deep enough through overburden to keep soil, sand, etc., out of a borehole. See also: standpipe.

stands

Connected joints of drill pipe racked in the derrick while changing the bit.

stank

a. To make watertight; to seal off; an airtight and watertight wall against old mine workings. See also: seal; sealed-off area.

b. A small cofferdam constructed of timber and made watertight with clay. c. See: stanking.

stanking

a. A watertight stopping or bulkhead.

b. The application of a waterproofing material to a stopping or bulkhead.

Stanley compensating diaphragm

A specially designed theodolite used as a direct reading tacheometer. See also: Beaman stadia arc.

stanley header

See: header.

stannary

a. A tin mine or tin works.

b. One of the regions in England containing tinworks and formerly placed under jurisdiction of special courts. Usually used in plural.

stannary courts

Eng. Courts in Cornwall and Devonshire for the purpose of regulating the affairs of tin mines and tin miners.

stannatores

An early name applied to Cornish tin miners.

stanniferous

Relating to or containing tin; as, stanniferous ore.

stannine

See: stannite.

stannite

a. A tetragonal mineral, Cu (sub 2) FeSnS (sub 4) ; zinc may replace iron; tannite group; metallic; in granular masses in veins associated with cassiterite. Syn: tin pyrites; bell-metal ore.

b. The mineral group briartite, cernyite, famatinite, hocartite, kuramite, luzonite, permingeatite, pirquitasite, sakuraiite, and stannite. c. Impure cassiterite. Syn: tin pyrites; stannine.

stannopalladinite

A hexagonal mineral (Pd,Cu) (sub 3) Sn (sub 2) (?) .

stannous chloride

See: salt of tin.

stannum

See: tin.

stantienite

A black variety of retinite having a very high oxygen content (23%). Syn: black amber.

Stanton diagram

Historically, a plot of the airflow friction coefficient against the Reynolds number is referred to as a Stanton diagram.

staple

a. A shaft that is smaller and shorter than the principal one and joins different levels.

b. An internal shaft connecting two coal seams. Also called staple pit. CF: winze.

staple shaft

a. An underground shaft, which does not penetrate to the surface.

b. A relatively small vertical pit connecting a lower seam to an upper seam. It corresponds to a rise or winze in metal mining. A staple shaft is an important drivage in horizon mining and may be used for dropping coal or stowing dirt to a lower level. It is often equipped with a spiral chute or an auxiliary winder system with a single cage and counterweight. See also: subincline.

star

In minerals, the presence of needlelike oriented inclusions aligned along crystallographic axes, generally in the plane normal to the c axis in the hexagonal and trigonal crystal systems. Syn: asteriated.

star antimony

Refined metallic antimony characterized by crystalline patterns resembling stars or fern leaves on its surface. Also called star metal.

starch

Used as depressant in flotation process. Alkaline starch (starch dissolved in dilute sodium hydroxide) is a flocculating agent used in purifying the water in coal-cleaning plants. Also known as amylum.

star drill

A tool with a star-shaped point used for drilling in stone or masonry.

star facet

Small triangular facet situated between the bezel facets and the table on the crown of an American (Tolkowski theoretical) brilliant-cut diamond.

star feeder

A rotating feeder consisting of a horizontal shaft fitted with radial blades running within a close-fitting cylindrical chamber provided with an inlet and an outlet. Also called star gate; star valve (undesirable usage).

star garnet

Variant of almandine.

starkeyite

A monoclinic mineral, MgSO (sub 4) .4H (sub 2) O ; rozenite group. Named for the Starkey Mine, Madison County, MO. Syn: leonhardtite.

Starlite

Trade name given by Kunz to artificially-colored blue zircon from Thailand.

star metal

See: star antimony.

star quartz

A variety of quartz containing within the crystal whitish or colored starlike radiations along the diametral planes. The asterism is due to the inclusion of submicroscopic needles of another mineral arranged in parallel fashion. In star blue quartz in Virginia and Texas, the other mineral is rutile. See also: asteriated quartz.

star reamer

A star-shaped tool for regulating the diameter of, or straightening, a borehole.

star ruby

A semiopaque to semitransparent asteriated variety of ruby normally having six chatoyant rays. CF: corundum cat's eye.

star sapphire

A semiopaque to semitransparent asteriated variety of sapphire normally with six rays resulting from the presence of microscopic crystals (e.g., rutile needles) in various orientations with the gemstone. See also: asteria. CF: corundum cat's eye.

star stone

a. An asteria; esp. a star sapphire.

b. Less correctly, any asteriated stone, including even petrified wood containing small starlike figures in its more transparent parts.

starter

a. A slightly larger drill used for making the beginning of a hole, the remainder of the hole being made with a drill of smaller gage known as a follower.

b. Pennsylvania. The miner who ascends to the battery to start the coal to run. See also: battery starter. c. Protective equipment to ensure that an electric motor does not receive too high a current when starting.

starter bar

A steel reinforcing bar embedded in the concrete and projecting through a construction joint to bind adjoining masses of concrete together.

starting barrel

A short core barrel used to begin coring operations when the distance between the drill chuck and the bottom of the hole, or to the rock surface in which a borehole is to be collared, is too short to permit use of a full 1.5-m-long or 3-m-long core barrel.

starting casing barrel

A short piece of casing to which a casing bit and shell are attached and used under the same conditions as a starting barrel. See also: starting barrel.

starting sheet

A thin sheet of metal used as the cathode in electrolytic refining.

starting submergence

In an air lift, the distance below the static head at which the air picks up water.

starvation

a. In comminution, avoidance of crowding in the machine by restricting rate of feed.

b. In conditioning for flotation, use of threshold quantity of collector agent to aid in selective adsorption by the desired species of mineral.

Stassfurt deposits

A series of saline minerals, found in the Triassic rocks at Stassfurt, Saxony, Germany, which include halite, anhydrite, kieserite, gypsum, and boracite.

stassfurtite

A massive variety of boracite found in Germany. It resembles a fine-grained white marble; sometimes has a subcolumnar structure.

statement of performance

A statement describing the scope and duty of a plant in terms, e.g., of the tonnage of coal treated per hour, the processes used, the separations effected and sizes produced; sometimes also used to express the results of plant operation.

state mine inspector

See: inspector; mine inspector.

state point

The psychrometric properties of air at given conditions, e.g., dry bulb temperature, wet bulb temperature, and barometric pressure.

stathmograph

An apparatus that records automatically, in the form of a graph, the loss of weight during the whole reduction of iron ores.

static air mover

See: air mover.

statically determinate frame

A structural frame in which the bending moments and reactions can be determined by the laws of statics alone.

statically indeterminate frame

A redundant frame in which the bending moments and reactions cannot be calculated from statical equations alone. See also: perfect frame.

static balance

A condition of rest created by inertia (dead weight) sufficient to oppose outside forces.

static efficiency

Is calculated in the same way as fan efficiency, but using a reading of static pressure at some point instead of total pressure. Was formerly widely quoted, and is still used to some extent, in relation to mine fans. See also: fan efficiency.

static E.P.

The electrode potential measured when no current is flowing between the electrode and the electrolyte.

static grizzly

A grizzly in the form of a stationary bar screen, often improvised from bars or rails set longitudinally, without cross bars. If used as a chute it has a slope of 35 degrees to 45 degrees . It may allow suitable pieces of coal or ore to pass over, and the unwanted small sizes drop through, or it rejects oversize pieces while allowing suitable material to drop through. See also: power grizzly.

static head

a. The height of a standing column of water as measured from the bottom of a borehole upward. Sometimes expressed in units of weight as measured at the bottom of the borehole.

b. In an air lift, the distance from the surface or top of the well casing to the normal surface of the water when not pumping. c. The sum of the suction and discharge heads. d. See: hydrostatic head; static level.

static level

The water level of a well that is not being affected by withdrawal of ground water.

static load

a. The basal pressure exerted by the weight of a mass at rest, such as the load imposed on a drill bit by the weight of the drill-stem equipment or the pressure exerted on the rocks around an underground opening by the weight of the superimposed rocks. Syn: dead load.

b. A load that is at rest and exerts downward pressure only, such as a hydrostatic load.

static metamorphism

A variety of regional metamorphism brought about by the action of heat and solvents at high lithostatic pressures, not at pressures induced by orogenic deformation. See also: load metamorphism. CF: thermal metamorphism.

static moment

The static moment of a section about an axis, Y, is also termed the first moment of the area about the axis. It is the sum of the products obtained by multiplying each component of an area, A, by its distance, X, from Y. See also: moment of inertia.

static penetration test

A penetration test in which the testing device is pushed into soil with a measurable force, as distinct from a dynamic penetration test in which the testing device is driven into the ground by blows from a standard hammer. See also: penetrometer; soil.

statics

That branch of mechanics dealing with the relations of forces that produce equilibrium among material bodies.

static switch

A device giving contactless control of a circuit; e.g., a transistor, thyratron, saturable reactor, etc.

static tube

A static tube has a shaped, solid nose, on the downstream side of which a number of small holes are positioned around the circumference. The holes are so placed that the pressure in the tube is that of the undisturbed airstream. Unlike the Pitot tube, the measured pressure is affected considerably both by the position of the stem of the tube in relation to the pressure holes, and by the distance between the holes and the nose tip. The static tube is considerably more sensitive to yaw than is the Pitot tube. See also: Pitot tube; Pitot-static tube.

static water level

The level of water in a well or borehole when pumping is not in progress.

station

a. See: underground station; tank station.

b. A reference point in surveying, marked at the surface by a metal plate set in concrete, or by a plug drilled into the roof of an underground working. c. A length of 100 ft (30.5 m), measured along a given line, which may be straight, broken, or curved. d. Any point on a straight, broken, or curved line whose position is indicated by its total distance from a starting point, or zero point. For example, station 4+47.2 identifies a point 447.2 ft (135.3 m) from the starting point, the distance being measured along a given line. e. A location on a conveyor system where bulk material is received or discharged. f. Any one of a series of stakes or points indicating distance from a point of beginning or reference. g. A setup point; i.e., a marked point on the ground, over which an instrument is to be placed.

stationary bar screen

A large-capacity screening or sorting appliance for coal or ore. It consists of a series of heavy metal bars arranged side by side and spaced at a definite distance apart. The bars are set at an angle so that material delivered at the upper end will just slide, and chutes are arranged to receive oversize at the lower end and undersize passing between the bars. The stationary bar screen is still used at many small mines. See also: Bradford breaker; resonance screen; screen.

stationary block

The relatively undeformed rocks beneath the plane of an overthrust fault. See also: autochthon.

stationary dredge

a. A dredge that is not self-propelled, the dredged material from which is discharged into either a hopper barge or a pipeline.

b. A fixed vessel with equipment for digging, washing, and concentrating alluvial deposits. See also: dredge.

stationary engine

An engine located on a fixed foundation, as distinguished from a portable engine.

stationary equipment

Stationary equipment is installed in a given location and is not moved from that location in performing its function. This includes equipment such as substations, pumps, and storage-battery charging stations.

stationary grizzly

The simplest of all separating devices and the cheapest to install and maintain. It consists of a series of fixed bars or rails spaced the required distance apart in order that the "undersize" may drop through. The use of a stationary grizzly is limited to coarse screening of dry material (aperture 2 in or 5.1 cm and larger), although it is sometimes used with openings as small as 3/4 in (1.9 cm), the efficiency dropping off in proportion. It is not satisfactory for moist or sticky material.

stationary inner-tube core barrel

See: rigid-type double-tube core barrel.

stationary jaw

The fixed jaw of a safety clamp or wrench. Syn: stationary slip. CF: anvil.

stationary mass

In some seismometers, a heavy weight, either suspended or supported, that, because of inertia, tends to remain quiescent during an earthquake. Syn: steady mass.

stationary-piston drive sampler

A piston-type sampler in which the position of the piston relative to the sample remains constant during the sampling operation.

stationary slip

See: stationary jaw.

station foreman

In metal mining, a laborer who supervises the haulage and handling of ore, timber, and mining supplies at a shaft station.

stations

Permanently marked points on the centerline of a tunnel . These stations may be outside of the tunnel and used for projecting the centerline into the tunnel, or they may mark the centerline inside the tunnel.

station yards haul

Equals the number of cubic yards multiplied by the number of 100-ft (30.5-m) stations through which it is moved.

statistical uniformity

A term describing that variation in quality of materials of manufactured goods that is stable and determinate, so that statistical analysis and prediction can be applied to it. See also: representative sample; level of control.

statistics

The collection, tabulation, and study of numerical facts and data. In industry, statistics indicate trends that would be almost impossible to establish by other means. The statistical method is useful in: (1) estimating the real value of work done, goods, or machines in terms of useful service and maintenance costs; and (2) estimating and forecasting profits and markets. See also: parameter.

stator

In a torque converter, a set of fixed vanes that change the direction of flow of fluid entering the pump or the next stage turbine.

statuary marble

A fine-grained saccharoidal marble used by sculptors. The best qualities are pure white and free from markings.

staurolite

A monoclinic mineral, Fe (sub 2) Al (sub 9) Si (sub 4) O (sub 22) (OH) (sub 2) ; pseudo-orthorhombic; Mohs hardness, 7.5; a common accessory in medium-grade regional metamorphic rocks; may be of gem quality; cruciform twins called fairy crosses. Syn: staurotide; cross-stone; grenatite; fairy stone; lucky stone.

stauroscope

A type of polariscope used to determine the direction of light polarization in a crystal for accurate measurement of angles of extinction. See also: polariscope.

staurotide

See: staurolite.

staurotypous

In mineralogy, having crosslike markings.

stave

a. A ladder step.

b. A wedge-shaped section placed around the die of a stamp to take up the side wear.

stavrite

An obsolete term for a type of biotite amphibolite.

stay

A diagonal brace or tie bar to stiffen or prevent movement of a structural component.

stay-bolt tap

A type of combination reamer and tap used extensively in locomotive-boiler work.

stead

S. Wales. Very thin bands of ironstone in coal measures.

Stead's reagent

An etching reagent, used in metallographic examination of steels, containing 100 mL methyl alcohol, 18 mL water, 2 mL concentrated hydrochloric acid, 1 g copper chloride, and 4 g magnesium chloride.

steady-flow process

A flow process in which none of the variables of flow changes with time.

steady-head tank

In connection with use of moderate pressure hydraulic water (e.g., in classification of ore pulps), a reservoir set above the draw-off points of the system, which maintains a full supply of water at a set height and therefore constant pressure.

steady mass

See: stationary mass.

steady point

A pointed steel bar that can be locked in a clamp, and is used to brace a drill frame against the ground.

steady-state creep

See: secondary creep.

steady-state velocity

The constant maximum detonation velocity achieved by an explosive charge of a given diameter, mixture and density; it is the velocity at which a detonation will sustain itself through a column of explosive.

stealite

Chiastolite, a variety of andalusite.

steamboat rolls

Those rolls in an anthracite breaker that are set farthest apart to break the coal into steamboat coal.

steam gas

Highly superheated steam.

steam hammer

A heavy hammer, moving between vertical guides, actuated by steam pressure.

steam-hoist man

See: hoistman.

steam infusion

The injection of steam into the coal seam by infusion tubes, connected to a small boiler through high-pressure hose pipes, to suppress the dust in situ. The technique and equipment are somewhat similar to water infusion. Owing to technical, safety, and other problems, water infusion is preferred.

steam jet

a. A system of ventilating a mine by means of a number of jets of steam at high pressure kept constantly blowing off from a series of pipes in the bottom of the upcast shaft.

b. A jet of steam to moisten the intake air current and thus keep the coal dust in the mine wet.

steam jet refrigeration

A method of cooling involving the use of steam nozzles to reduce the pressure in a water chamber so that the water boils at a low temperature; since heat is drawn from the water, it is thus cooled.

steam main

A horizontal pipe for carrying live steam from a boiler to radiators, a steam engine, or other steam consuming device.

steam point

See: point.

steam shovel

An excavating machine in which a large dipper is operated by steam power. Used for stripping purposes and in open-pit mining, esp. for iron and coal. A similar shovel is now operated by electricity, gasoline, and diesel engines.

steam shovel mine

An opencut mine in which steam shovels or other power shovels are used for loading cars.

steam stamp

A crushing machine consisting of a vertical stamp shaft that is forced down to strike its blow, and lifted up preparatory to striking the next, by a steam piston.

steam thawing

A method of dredging permanently frozen ground in Alaska and the Yukon Territory in which steam is forced through pipes that are fitted with steel points on one end and a driving head on the other end so that the pipes can be hammered into the frozen gravel. Thawing by steam is a slow and costly process. See also: thawing.

steam winder

The most common type of steam winder is the two-cylinder double-acting horizontal engine driving direct on the drum shaft. These engines, which are made with cylinders up to 42 in (1.1 m) in diameter and with a 84-in (2.1-m) stroke, possess the merit of simplicity and ease of control. The two cylinders act on cranks set at 90 degrees to each other and are large enough for either to start the engine from rest against a full load, since one may happen to stop at dead center (i.e., with the piston at the end of its stroke, in which position it can exert no turning moment on the crank).

Steart fan

A propeller or axial-flow fan developed by Steart in Australia. See also: fan.

steatite

a. A compact, massive, fine-grained, fairly homogeneous talc-rich rock.

b. Gray-green or brown massive impure talc that is carved easily into ornamental objects. Syn: lardite; lard stone; soapstone; soap earth. See also: talc.

steatite talc

A relatively pure or high-grade variety of talc suitable for use in electronic insulators, the purest commercial form of talc. Syn: French chalk.

steatitization

Introduction of, alteration to, or replacement by, talc (steatite); esp. the act or process of hydrothermal alteration of ultrabasic rocks that results in the formation of a talcose rock (such as steatite, soapstone, or relatively pure concentrations of talc).

Stebinger drum

A delicate vertical-angle adjustment for the vernier on the alidade, graduated in hundredths of a revolution. See also: gale alidade. CF: tangent screw.

steel

a. An iron-base alloy, malleable in some temperature range as initially cast, containing manganese, usually carbon, and often other alloying elements. In carbon steel and low-alloy steel, the maximum carbon is about 2.0%; in high-alloy steel, about 2.5%. The dividing line between low-alloy and high-alloy steels is generally regarded as being at about 5% metallic alloying elements. Steel is to be differentiated from two general classes of irons: the cast irons, on the high-carbon side and the relatively pure irons, such as ingot iron, carbonyl iron, and electrolytic iron, on the low-carbon side. In some steels containing extremely low carbon, the manganese content is the principal differentiating factor, steel usually containing at least 0.25%; ingot iron contains considerably less.

b. The borer, consisting of shank, shaft, and bit or cutting edge; used for rock-drilling with drifters or jackhammers. c. In air hammers, the hollow or solid steel bar that connects the hammer with the cutting tool.

steel arch

Curved length of steel, usually of H-section, used for supporting mine roadways. Two-, three-, or four-segment arches are available, with straight leg, splayed leg, horseshoe, or circular design; in double radius or with welded baseplate. See also: Usspurwies arch; Toussaint-Heintzmann arch; steel support; steel ring.

steel band belt

A belt of relatively thin carbon or stainless strip steel alloyed and heat treated to withstand continued flexing over pulleys.

steel belt

Thin, flat, steel belts ranging from 0.008 to 0.035 in (0.02 to 0.09 cm) in thickness and from 7/8 to 8 in (2.2 to 20.3 cm) in width have been successfully used. The pulleys should be faced with a thin layer of cork. Steel belts can be run at speeds as high as 10,000 ft/min (3.0 km/min). It has been claimed that a 4-in (10.2-cm) steel belt will transmit as much power as a 19-in (48.3-cm) leather belt.

steel bit

The cutting tool at the end of the drill steel. Various bit shapes are used, the three commonest being the single chisel bit (used only for hand drills); the double chisel bit (used for fairly soft rock), and the cross bit (used for hard rock and for general purposes). See also: tungsten carbide bit; chisel bit; cross-chopping bit.

steel boy

A youngster who carries drills to the miners, and collects dull drills and sees that they are returned to the blacksmith shop.

steel cable

A flexible rope, the strands of which are steel wires. See also: cable.

steel-cable conveyor belt

A rubber conveyor belt in which the carcass is composed of a single plane of steel cables that acts as a longitudinal tension-carrying member and includes two or more plies of fabric to provide transverse strength and hold the cables together.

steel casing

A pipe to support the walls of a borehole in loose ground. The casing is secured in position by a concrete block or by the cross beams of the platform. It is driven down from the surface and follows the drilling operation closely or sometimes even precedes the borehole in sand or very loose ground. See also: borehole casing.

steel centralizer

On a wagon drill, a guide to hold the starting steel in proper alignment.

steel erector

A skilled member of a team specially trained to erect steel framed buildings, bridges, and other steel structures.

steel guides

Steel rails, rods, or bars fixed in a vertical shaft to guide the cage and prevent it from swinging. See also: fixed guides.

steel jack

a. A screw jack esp. suitable in mechanical mining. Under headers at or near the face, steel jacks or posts are used for upright timbers to be replaced as equipment advances. Also called steel post.

b. See: sphalerite.

steelmaking

The process of making steel from solid or molten pig iron, with or without admixture with steel scrap. The processes used are the Bessemer, open-hearth, crucible, electric arc, high-frequency induction, and duplex.

steel mill

A mill where steel is made, processed, and shaped.

steel needle

An instrument used in preparing blasting holes; used before the safety fuse was invented.

steel ore

A name given to various iron ores and esp. to siderite, because it was supposed to be esp. adapted for making steel by the earlier and direct process.

steel plate conveyor

See: plate conveyor.

steel press

A machine for compressing molten steel in casting to improve the quality of the product.

steel prop

A steel upright or post used to support the nether roof at a longwall or other face. It usually incorporates a yielding device. See also: hydraulic prop; mechanical yielding prop; self-advancing supports.

steel puller

A hinged clamp on the bottom of a hand drill.

steel rectangular shaft supports

A shaft support consisting of H-beams, I-beams, angles, and sheeting. The design is somewhat similar to that used for timber. Bolts, rivets, and fastening angles are used to connect and secure the steel members. The fastening angles are riveted to the beams. The addition of galvanized-iron corrugated wall sheets (or laggings) form a secure and fireproof shaft. See also: permanent shaft support; barring; bunton; wallplate; lagging.

steel ring

Ring- or horseshoe-shaped support for underground traveling way. Also called arch ring. See also: steel arch.

steel scrap

Miscellaneous pieces of steel, old and new, used in the bath for steel making, esp. in the open-hearth furnace.

steel separation door

A steel door specially erected for the purpose of being closed only in an emergency, such as a fire or an explosion. Steel is necessary for strength and to avoid destruction by fire. Steel doors may also be used as separation doors in the vicinity of the pit bottom or fan drift. Also called safety door; emergency door. See also: separation door.

steel sets

Used in main entries of coal mines and in shafts of metal mines in the United States. The sections have I-beams for caps and H-beams for posts or wall plates, the H-section giving equal stiffness in two directions at right angles to each other. Steel sets of various shapes are coming into wide use in deep European coal mines where pressures are so great that timber would not be satisfactory. See also: steel tunnel support.

steel sheet piling

Piling composed of interlocking rolled steel sections driven vertically into the ground with guide walings in place before excavation starts.

steel shot

Chilled cast iron drops. Syn: chilled shot.

steel support

A straight or curved length of steel, usually of H or channel section, used for support purposes in mine roadways, faces, or shafts. A steel support (1) possesses a high degree of permanency or long service; (2) ensures a minimum area of excavation for given dimensions in the clear; and (3) is fireproof. In return airways and shafts, a chrome-nickel-copper steel is sometimes used to counteract the corrosive air. For high-strength roof bars best results are obtained by the use of heat-treated low-alloy steels of the carbon manganese type. See also: arch girder; steel arch; straight girder support; support; Usspurwies arch; Toussaint-Heintzmann arch.

steel tunnel support

Tunnel-support systems made of steel are roughly of five types: continuous rib; rib and post; rib and wallplate; rib, wallplate, and post; and full circle rib. (1) A continuous rib system is usually made in two pieces for maximum speed of erection, lowest first cost, and lowest erection cost. Sometimes used in three or four pieces to meet special conditions and the following methods of attack: full face, side drift, and multiple drift. (2) A rib and post system is employed with the following methods of attack: full face in tunnels whose roof arch makes an angle with the sidewall; multiple drift and side drift in tunnels of such large size that two-piece continuous ribs cannot be shipped and/or handled; and heading and bench and top heading for support in the drift (with truss panels) for early support to roof. (3) In a rib and wallplate system, the rib is also usually made in two pieces for maximum speed of erection, lowest first cost, and lowest erection cost. It is sometimes used in three or more pieces to meet special conditions and with the following methods of attack: heading and bench, top heading, and full face. This type is esp. applicable to circular and high-sided tunnel sections where only a light roof support is needed. (4) In a rib, wallplate, and post system, these elements of support are used with the following methods of attack: heading and bench and top heading--for quick support to a roof; side drift--in large tunnels with bad rock conditions requiring quick support; and full face--for favorable rock where support is not needed tight to the face, for a tunnel whose roof makes an angle with the sidewall, and where post and rib spacing differ; and (5) A full circle rib--this method is used with the following attack: full face--in tunnels in squeezing, swelling and crushed rock, or any rock that imposes considerable side pressure, also where bottom conditions make it impossible to carry roof loads on foot blocks, and in earth tunnel conditions sometimes encountered in rock tunnels; and heading and bench--under earth tunnel conditions with joints at spring line. The inverted strut is used where mild side pressures are encountered and also to prevent the bottom from heaving. A full circle with ribs closely spaced is heavily lagged for heavy loads associated with squeezing conditions. See also: steel sets. Syn: tunnel support.

steel wire rope

See: wire rope.

steenstrupine

A trigonal mineral, Na (sub 14) Ce (sub 6) Mn (super +2) Mn (super +3) Fe (sub 2) (Zr,Th)(Si (sub 6) O (sub 18) ) (sub 2) (PO (sub 4) ) (sub 7) .3H (sub 2) O .

steep

See: brasque.

steep gradient

In general, in coal mining, an inclination (of a roadway, working, or coal seam) steeper than 1:4.

steeply inclined

Deposits and coal seams having a dip of from 40 degrees to 60 degrees .

steering brake

A brake that slows or stops on one side of a tractor.

steering clutch

A clutch that can disconnect power from one side of a tractor.

Stefan-Boltzmann Law

a. The energy radiated in unit time by a black body is given as E=K(T (super 4) -T (sub 0) (super 4) ) , where T is the absolute temperature of the body, T (sub 0) the absolute temperature of the surroundings, and K is a constant.

b. The statement that the radiant flux of a black body is equal to the absolute temperature to the fourth power times the Stefan-Boltzmann constant of (5.6696+ or -0.001)X10 (super -8) W (m) (super -2) (K) (super -4) .

steigerite

A monoclinic mineral, AlVO (sub 4) .3H (sub 2) O ; weakly radioactive; forms coatings on highly weathered sandstones of the Colorado-Utah carnotite region.

stein

Stonework used to secure the sides of a shaft.

steinmannite

A variety of galena with part of the lead replaced with antimony and arsenic.

stele

In coal, primarily the vascular tissues of the axis of a vascular plant. It consists of two parts: the xylem that carries water from the roots, and the phloem that carries the food.

stell

See: sprag.

stellate

Said of an aggregate of crystals in a starlike arrangement; e.g., wavellite.

stell prop

A steel or timber prop fixed firmly between the roof and the floor at the end of a longwall face and from which a coal cutter is hauled by rope when cutting. A stell prop may also be used as part of a belt-tensioning arrangement or a return sheave. Syn: anchor prop. See also: conveyor creep.

stem

a. To insert and pack stemming in a shothole. See also: tamp.

b. The assemblage of drill rods in a borehole connecting a drill bit and core barrel to the drill machine. c. The heavy iron rod acting as the connecting link between the bit and the balance of the string of tools on a churn rod in a borehole connecting a drill bit drill. d. Frequently used as a syn. for ram or tamp. See: stemming.

stem bag

Fire-resisting paper bag, about 8 in (20.3 cm) long, filled with dry sand for stemming shotholes in coal or hard headings. See: water-ampul stemming.

stemmer

A wooden rod used by shot firers for inserting the explosive cartridges and stemming material in shotholes. The stemmer must be long enough to reach the back of the shothole, and has a diameter 1/8 in (3.2 mm) larger than the cartridges. Metal is not permitted in any part of a stemmer used in British coal mines. Also called tamping rod or stick; beater. See also: tamping; scraper; break detector.

stemming

a. The material (limestone chippings or sand and clay) used to fill a shothole, after the explosive charge has been inserted, to prevent the explosion from blowing out along the hole. In tunnels and hard headings, the stemming may be blown in by a hurricane air stemmer.

b. The act of pushing and tamping the material in the hole. See also: water-ampul stemming; tamp. c. Inert material packed between the explosive charge and the outer end of the shothole, or between adjacent charges in deck charging. d. See: tamping; stem.

stemming rod

A nonmetallic rod used to push explosive cartridges into position in a shothole and to ram tight the stemming. Syn: stemming stick. See also: tamping stick; tamping rod.

stemming stick

See: stemming rod.

stench

A substance with a distinctive, disagreeable odor put in the air current to warn underground workers of fire or other emergency; ethyl mercaptan is commonly used.

stench capsule

A fire-warning device designed to be bolted to a flat surface that may rise to a dangerous temperature. It consists of a cavity filled with 20 cm (super 3) of ethyl or butyl mercaptan alone or with other stench agents and is sealed with a fusible plug in a brass container with a hexagonal head, arranged to liberate the stench agent at any temperature chosen. Tests in pits have shown that a strong smell could be detected 1.7 miles (2.7 km) from the discharge point 25 to 30 min after the device operated.

stenonite

A monoclinic mineral, (Sr,Ba,Na) (sub 2) Al(CO (sub 3) )F (sub 5) .

stent

a. The amount of work expected from a coal miner in a day or week. See also: stint.

b. See: pitch. c. Corn. Tourmaline and quarz veins in kaolinized granite. d. U.K. Rubble; waste. e. U.K. Extent or limit, as of a pitch or bargain.

stenting

N. of Eng. See: stenton.

stenton

A connecting roadway between two adjacent roadways that may be used for ventilation purposes. Also called air slit; crosscut; cross hole; thirling; througher; spout. Syn: crosscut. See also: air slit; breakthrough; pillar-and-stall.

step

a. Fault; a small fault; a small fault in a stepped series of faults.

b. A small offset on a piece of core or in a drill hole resulting from a sudden sidewise deviation of the bit as it enters a hard, tilted stratum or rock underlying a softer rock. CF: kick. c. One of several terracelike or stairstep concentric configurations on the crown of a diamond bit. See also: step-face bit. d. A treatment of one part of a sample in a sample divider (thus a pass consists of one or more steps). e. The action of setting a lock gate into a vertical position.

step cut

a. A mode of cutting gems in steplike facets.

b. A form of cutting employed for stones not deeply colored when they are not cut as brilliants; a simple typical form is that of a stepped pyramid with the apex sliced off. Also called trap cut. c. A style of cutting, widely used on colored gemstones, in which long, narrow, four-sided facets form in a series or row parallel to the girdle and decrease in length as they recede above and below the girdle, giving the appearance of steps. The number of rows, or steps, may vary, although it is usually three on both the crown and pavilion. Different shapes of step cuts are described by their outline; e.g., rectangular or square step cut. Syn: trap cut. CF: emerald cut.

step-face bit

A thin-nosed bit with diamonds set in several concentric terracelike rows that form the outside wall.

step fault

a. One of a set of parallel, closely spaced faults over which the total displacement is distributed. CF: fault zone. Syn: multiple fault; distributive fault.

b. One of a series of low-angle thrust faults in which the fault planes step both down and laterally in the stratigraphic section to lower glide planes. Step faulting is due to variation in the competence of the beds in the stratigraphic section. c. A series of parallel faults that, all inclined in the same direction, gives rise to a gigantic staircase; hence these are called step faults. Each step is a fault block and its top may be horizontal or tilted.

stephanite

An orthorhombic mineral, Ag (sub 5) SbS (sub 4) ; soft; metallic; sp gr, 6.2 to 6.3; in veins; a source of silver. Syn: brittle silver ore; black silver; goldschmidtine.

Stephenson lamp

An early type of coal miners' lamp. It had a glass chimney surrounded by a wire gauze about 2 in (5.1 cm) in diameter. The glass chimney was covered by a perforated copper cap, and the air was fed to the flame from below through small holes and wire gauze in a lateral extension of the oil vessel. The lamp was unsafe; it passed flame when the velocity of the air current exceeded about 8 ft/s (2.4 m/s). See also: safety lamp.

steppe

An extensive, treeless grassland area in the semiarid mid-latitudes of southeastern Europe and Asia. It is generally considered drier than the prairie which develops in the subhumid midlatitudes of the United States.

stepped foundation

See: benched foundation.

stepped longwall

A system of longwall stalls in which the faces are carried forward in a steplike formation, one stall about 5 yd (4.6 m) in advance of the next stall. It is claimed to have advantages when the roof is friable. See also: top holes. Syn: hitch-and-step.

stepped stope

The term implies that mining at one face is stepped aside from that below so as not to hinder the work at it. Syn: advance stope.

stepping ahead

Term used in dredging operations when the digging spud is dropped, the other spud is raised, and the dredge is ready to begin a new cut.

step reef

See: step vein.

step socket

A special form of socket for use on locked-wire rope.

step up

To increase the voltage of (a current) by means of a transformer.

step vein

A vein alternately cutting through the strata of country rock and conforming with them. Syn: step reef.

stercorite

A triclinic mineral, H(NH (sub 4) )Na(PO (sub 4) ).4H (sub 2) O . Syn: microcosmic salt.

stereocomparator

A stereoscope for accurately measuring the three space coordinates of the image of a point on an aerial photography; it is used in making topographic measurements by the comparison of stereoscopic photographs.

stereogram

a. A graphic diagram on a plane surface, giving a three-dimensional representation, such as projecting a set of angular relations; e.g., a block diagram of geologic structure, or a stereographic projection of a crystal.

b. A stereoscopic pair of photographs correctly oriented and mounted for viewing with a stereoscope. Syn: stereographic projection; stereograph.

stereograph

See: stereogram.

stereographic projection

a. A map projection in which meridians and parallels are projected onto a tangent plane, with the point of projection on the surface of the sphere diametrically opposite to the point of tangency of the projecting plane. Any point of tangency may be selected (at a pole, on the equator, or a point in between).

b. A similar projection used in optical mineralogy and structural geology, made on an equatorial plane (passing through the center of the sphere) with the point of projection at the south pole. Syn: stereogram.

stereometric map

A relief map made by the application of the stereoscopic principle to aerial or terrestrial photographs. Syn: stereotopographic map.

stereoscopic principle

The formation of a single, three-dimensional image by simultaneous vision with both eyes of two photographic images of the same terrain taken from different camera stations.

stereoscopic vision

Simultaneous vision with both eyes in which the mental impression of depth and distance is obtained, usually by means of two different perspectives of an object (such as two photographs of the same area taken from different camera stations); the viewing of an object in three dimensions. Syn: stereoscopy; stereovision.

stereoscopy

See: stereoscopic vision.

stereosphere

a. That part of the Earth's crust that lies above the level of compensation, or the top of the asthenosphere. See also: asthenosphere.

b. The relatively strong outer shell of the Earth. c. A term that was originally proposed for the innermost shell of the Earth's mantle, but is also used as equivalent to the lithosphere.

stereotopographic map

See: stereometric map.

stereovision

See: stereoscopic vision.

sterilized coal

That part of a coal seam that, for various reasons, is not mined.

sterling silver

A silver alloy containing at least 92.5% silver, the remainder being unspecified but usually copper.

sternbergite

An orthorhombic mineral, AgFe (sub 2) S (sub 3) ; cubanite group; forms tabular crystals or soft flexible laminae. Syn: flexible silver ore.

sterny

Scot. Rough; coarse-grained or crystalline, for example, sterny limestone.

sterrettite

See: kolbeckite.

stetefeldite

A somewhat uncertain compound containing silver, copper, iron, antimony, sulfur, and water [Ag (sub 2) Sb (sub 2) (O,OH) (sub 7) ] (?).

Stetefeldt furnace

A furnace for the chloridizing and roasting of silver ores, and also for roasting fine copper ores low in sulfur. Provision is made for an auxiliary fireplace.

stevensite

A monoclinic mineral, Ca/2) (sub 0.3) Mg (sub 3) Si (sub 4) O (sub 10) (OH) (sub 2) ; smectite group; with no tetrahedral substitution of Al for Si, its layer charge arises from octahedral vacancies. Syn: aphrodite.

stewartite

a. A triclinic mineral, MnFe (sub 2) (PO (sub 4) ) (sub 2) (OH) (sub 2) .8H (sub 2) O ; dimorphous with laueite; forms minute crystals and tufts of fibers in pegmatites.

b. A steel-gray, ash-rich, fibrous variety of bort containing iron, having magnetic properties, in the diamond mines of Kimberley, South Africa.

stey

Scot. Steep; highly inclined.