Appendix:Dictionary of Mining, Mineral, and Related Terms/F/2

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The unobstructed distance that the wind can travel to any point when raising waves.


Having a disagreeable odor caused by the occurrence of certain bituminous substances or of hydrogen sulfide. This odor is apparent when some varieties of limestone and quartz are broken or are rubbed vigorously.

fetid calcite

A variety of calcite that emits an offensive odor when dissolved in dilute hydrochloric acid. The odor is due to trace sulfides and other impurities. See: swinestone.


a. To cover or line the hearth of (a reverberatory furnace) with fettling.

b. To clean and smooth (as a metal or plastic) after casting or molding. c. To remove fins, mold marks, and rough edges from dry, or nearly dry, ware.


a. Protecting the bottom of the open-hearth furnace with loose material, such as ore, sand, etc.; also, the material so used.

b. The process of repairing a steel-furnace hearth, with dead-burned magnesite or burned dolomite, between tapping and recharging the furnace.


See: firestone.


See: fea.


The smallest single strand of asbestos or other fibrous material.


A single fiber, which cannot be separated into smaller components without losing its fibrous properties or appearance.


The texture of metamorphic rocks resulting from the development during recrystallization of minerals with a fibrous habit. See also: nematoblastic.


A monoclinic mineral, Fe(SO (sub 4) )(OH).5H (sub 2) O ; forms fine fibrous crusts or masses associated with melanterite, copiapite, jarosite, and other secondary sulfates.

fibrogenic dust

See: pulmonary dust.


a. A fibrous, felted variety of sillimanite.

b. One of three crystalline forms of aluminum sillicate, Al (sub 2) SiO (sub 5) , the others being andalusite (low temperature) and kyanite (high temperature). Sillimanite occurs commonly as felted aggregates of exceedingly thin fibrous crystals (hence the name fibrolite) in contact metamorphosed aluminous sediments such as mudstones, shales, etc. Crystals of a pale sapphire blue are used as gems.

fibrolite cat's-eye

A pale greenish variety of sillimanite having fibrous inclusions; when cut, produces a chatoyant effect, but not a well-defined cat's-eye.


a. Applied to minerals that occur as fibers, such as asbestos. Syn: asbestiform.

b. Consisting of fine threadlike strands, e.g., satin spar variety of gypsum.

fibrous aggregate

A crystalline aggregate composed of closely packed fibers.

fibrous anthraxylon

Thin strands of anthraxylon having the appearance of threads in thin sections.

fibrous calcite

Translucent calcite composed of fibrous crystals, which, like fibrous gypsum, with which it is often confused, causes a silky sheen. When cut cabochon, it produces a girasol or chatoyant effect, but not a true cat's-eye. Also like fibrous gypsum, it is called "satin spar" but less correctly.

fibrous gypsum

See: satin spar. CF: fibrous calcite.

fibrous peat

a. Peat composed of the fibrous remains of plants. It is fibrous, spongy, moderately tough, and nonplastic. It does not shrink much on drying. Also called woody peat. See also: pseudofibrous peat; amorphous peat.

b. Firm, moderately tough peat in which plant structures are only slightly altered by decay. It shrinks little on drying.

fibrous structure

a. If the crystals in a mineral aggregate are greatly elongated and have a relatively small cross section, the structure or texture is fibrous. The fibers may be parallel, as in crocidolite and sometimes in gypsum and cerussite. When the fibers are very fine, they may impart a silky luster to the aggregate, as in crocidolite and satin-spar gypsum. There is also a feltlike type. Fibrous crystals may radiate from a center, producing asteriated or starlike groups, either coarse or fine, as frequently observed in pyrolusite, wavellite, natrolite, and tourmaline, and sometimes in stibnite and other minerals. Also called fibrous texture.

b. In forgings, a structure revealed as laminations, not necessarily detrimental, on an etched section or as a ropy appearance on a fracture, not to be confused with the silky or ductile fracture of a clean metal. c. In wrought iron, a structure consisting of slag fibers embedded in ferrite. d. In rolled-steel plate stock, a uniform, fine-grained structure on a fractured surface, free of laminations or shale-type discontinuities. As contrasted with definition b., it is virtually synomous with silky or ductile fracture.

fibrous texture

In mineral deposits, a pattern of finely acicular, rodlike crystals, e.g., in chrysotile and amphibole asbestos.

fibrous wax

A fibrous variety of ozocerite, a natural paraffin wax. See also: ozocerite.


A monoclinic mineral, dimethyl-isopropyl-perhydropenanthrene, C (sub 19) H (sub 34) ; translucent white; in fossil wood or conifers.

fiducial interval

A measure of confidence in precision of a set of sample data. For a given numerical value of fiducial interval, the number of samples required from a given deposit to give an accurate measure of its value can be determined.

fiducial mark

In photogrammetry, an index or point used as a basis of reference; one of usually four index marks connected with a camera lens (as on the metal frame that encloses the negative) that form an image on the negative or print such that lines drawn between opposing points intersect at and thereby define the principal point of the photograph. Syn: collimating mark.

fiducial time

A time marked on a record to correspond to some arbitrary time. Such marks may aid in synchronizing different records or may indicate a reference, such as a datum plane.


a. A region or area that possesses or is characterized by a particular mineral resource; e.g., goldfield, coalfield.

b. A broad term for the area, away from the laboratory and esp. outdoors, in which a geologist makes observations and collects data, rock and mineral samples, and fossils. c. That space in which an effect, e.g., gravity or magnetism, occurs and is measurable. It is characterized by continuity; i.e., there is a value associated with every location within the space. d. A section of land containing, yielding, or worked for a natural resource; e.g., a coalfield, an oilfield, or a diamond field. A large tract or area, as large as many square miles, containing valuable minerals. See also: coalfield. e. The immediate locality and surroundings of a mine explosion. f. A colliery, or firm of colliery proprietors.

field capacity

The quantity of water held by soil or rock against the pull of gravity. It is sometimes limited to a certain drainage period, thereby distinguishing it from specific retention, which is not limited by time. Syn: field-moisture capacity; normal moisture capacity.

field classification of rocks

A classification of rocks made in the field. It is based on features distinguishable in hand specimens by using a hand lens, a knife, an acid bottle, etc. The classification may be refined or modified by subsequent examination with a microscope or other techniques that are generally used in a laboratory.

field compaction trial

Tests carried out under site conditions to determine the best combination of (1) type of compaction equipment; (2) thickness of loose soil layer; (3) number of passes; and (4) moisture content (where variation is possible) in order to achieve the highest possible soil densities.

field geology

Geology as practiced by direct observation in the field; original, primary reconnaissance; field work.

field investigation

In reference to experimental-mine tests, the investigation made at a mine when a large sample is taken for testing at the experimental mine; this investigation includes the taking of road dust, rib dust, mine air, and standard coal samples, and the noting of conditions affecting the safety of the mine.


A zinciferous variety of tetrahedrite. CF: goldfieldite.

field-laboratory operator

Person who analyzes mine water for acid, copper, and iron content by removing samples of water that flow to and from the precipitation drum, and who performs routine chemical tests.

field-moisture capacity

See: field capacity.

field work

Work done, observations taken, or other operations, as triangulation, leveling, making geological observations, etc., in the field or upon the ground.

fiery dragon

See: toadstone.

fiery heap

Eng. A deposit of rubbish and waste or unsalable coal that ignites spontaneously.

fiery mine

a. A mine in which the seam or seams of coal being worked give off a large amount of methane.

b. Mine in which there is danger of explosion due to coal dust or flammable gas. c. A gassy mine; a mine where gas ignitions and outbursts have occurred in the past.

fifth wheel

a. The weight-bearing swivel connection between highway-type tractors and semitrailers.

b. A wheel used to automatically operate the dump mechanism of mine ore cars.

figure cuts

See: V-cut.

figure stone

See: agalmatolite.

filar micrometer

An instrument, that in its usual form consists of an ocular containing a fine wire that can be moved across the field by means of a thumbscrew for the purpose of measuring size.


Having the shape of a thread or filament; e.g., native silver. Syn: wiry. CF: capillary.

filiform texture

Threadlike crystals of one mineral embedded in another mineral; e.g., rutilated quartz.


a. Delicate ornamental work, used chiefly in decorating gold and silver.

b. Naturally occurring native metals (e.g., gold, silver, or copper) in lacelike form.


a. Manmade deposits of natural earth materials (e.g., rock, soil, and gravel) and waste materials (e.g., tailings or spoil from dredging), used (1) to fill an enclosed space, such as an old stope or chamber in a mine, (2) to extend shore land into a lake or bay, or (3) in building dams. See also: hydraulic fill; backfill.

b. Soil or loose rock used to raise the surface of low-lying land, such as an embankment to fill a hollow or ravine in railroad construction. Also, the place filled by such an enbankment. c. The depth to which material is to be placed to bring the surface to a predetermined grade. d. Any sediment deposited by any agent so as to fill or partly fill a valley, sink, or other depression. e. Manmade deposits of natural soils and waste material. f. Material deposited or washed into a cave passageway. Fill is generally prefixed by a word describing its dominant grain size; e.g., sand fill, silt fill, clay fill, gravel fill, etc. g. Material used to fill a cavity or a passage. An embankment to fill a hollow or a ravine, or the place filled by such an embankment. Also, the depth of the filling material when it is in place. As a verb, to make an embankment in or to raise the level of a low place with earth, gravel, or rock. h. Tailings, waste, etc., used to fill underground space left after extraction of ore. Termed "hydraulic fill" if flushed into place by water. See also: pack. i. Detrital material partly or completely filling a cave. Syn: drift. j. The unit charge of batch into a tank or pot. k. Eng. To load trams in the mine. l. An earth or broken rock structure or embankment. m. Soil that has no value except bulk.

filled valley

A wide-basin valley, in an arid or semiarid region, that contains abundant alluvium in the form of fans, flood plains, and lake deposits.


See: mineral filler.

filler and drayer

A worker who fills tubs at the coal face and pushes them to the main haulage road.

fill factor

The approximate load the dipper is carrying, expressed as a percentage of the rated capacity. The fill factor is commonly called the dipper factor for shovels or the bucket factor for draglines.


a. The waste material used to fill up old stopes or chambers.

b. The loading of trams, conveyors, tubs, or trucks with coal, ore, or waste; the place where loading occurs. c. Allowing a mine to fill with water. d. Clogging of the abrasive coat by swarf. It may be reduced in many operations by using an opencoat construction or a lubricant. See also: swarf. e. Loading of mineral into mine trucks; shoveling onto conveyors; gob stowing; packing old stopes with waste. f. Material such as waste, sand, ashes, and other refuse used to fill in worked-out areas of excavation. g. Backfill.


a. A term used in flotation meaning a coating, layer, or thin membrane.

b. A thin layer of a substance, at the most a few molecules thick, generally differing in properties from other layers in contact with it.

film coefficient

The heat transferred by convection per unit area per degree temperature difference between the surface and the fluid. Also called unit convection conductance; surface coefficient.

film flotation

Early stage in development of modern flotation process for concentration of minerals, notably sulfides. The containing pulp was agitated with oil that then floated up, carrying selected minerals. This mineralized film was then overflowed or skimmed off. See also: froth flotation; flotation.

film mica

Knife-trimmed mica split from the better qualities of block mica to any specified range of thicknesses between 0.0012 in and 0.004 in (30.5 mu m and 102 mu m).

film-sizing tables

Tables used in ore dressing for sorting fine material by means of a film of flowing water. These tables may be considered as surface tables, from which the products are removed before they have found a bed, so that the washing is always done on the same surface; also building tables or buddles, on which the products are removed after they have formed a bed. These use the relative transporting power of a film of water flowing on a quiet surface, which may be either rough or smooth, to act upon the particles of a water-sorted product. The smaller grains, of high specific gravity, are moved down the slope slowly or not at all by the slow undercurrent; the larger grains, of lower specific gravity, are moved rapidly down the slope by the quick upper current.


a. A device for separating suspended solid particles from liquids, or fine dust from air. It incorporates a membrane on which the solids are retained. See: bag filter; drum filter; Genter filter; plate-and-frame filter. See also: vacuum filtration.

b. To subject to the action of a filter; to pass a liquid or a gas through a filter for the purpose of purifying, or separating, or both. To act as a filter; to remove from a fluid by means of a filter; to percolate. c. An electronic device in seismic instruments that permits selection of frequency characteristics appropriate for the ground motion it is desired to record. d. A layer, or a combination of layers, of pervious materials designed and installed in such a manner as to provide drainage and yet prevent the movement of soil particles by flowing water. Also called protective filter. e. To utilize a filter, as to clarify or purify a liquid or gas.

filter aid

a. A low-density, inert, fibrous, or fine granular material used to increase the rate and improve the quality of filtration.

b. Diatomaceous earth, used either to coat a filter cloth or as a thick filtering layer that can be plowed off with its load of cake from a rotating drum filter.

filter bed

a. A general name for a pond or tank with a bottom or bed used for filtering purposes.

b. A pond or tank having a false bottom covered with sand, and serving to filter river or pond water. c. A fill of previous soil that provides a site for a septic field.

filter cake

a. The compacted solid or semisolid material separated from a liquid and remaining on a filter after pressure filtration.

b. The layer of concentrated solids from the drilling mud left behind on the walls of a borehole, or on a filter paper in filtration tests on mud.

filter-cake texture

The physical properties of a cake as measured by toughness, slickness, and brittleness.

filter cloth

The fabric used as a medium for filtration; e.g., nylon cloth, blanket cloth, finely woven wire mesh, or finely woven glass thread. Syn: press cloth.

filtered light

Light that has passed through a colored-glass filter, absorbing some hues and permitting others to pass through.

filter feed trough

A tank containing the pulp to be filtered, generally fitted with an agitator to maintain the solids in the pulp in suspension, and in which the drum or disk of a rotary vacuum filter is partially immersed.

filtering stone

Any porous stone, such as sandstone, through which water is filtered.

filter loss

The amount of fluid delivered through a permeable membrane in a specified time.

filter press

A form of pressure filter, noncontinuous in operation; used in coal preparation for the removal of water from slurries, tailings, and similar products.

filter pressing

A process of magmatic differentiation wherein a magma, having crystallized to a mush of interlocking crystals in liquid, is compressed by Earth movements and the liquid moves toward regions of lower pressure, thus becoming separated from the crystals. Syn: filtration differentiation.

filter pump

An aspirator for hastening the process of filtering by creating a partial vacuum.

filter stick

Short glass tube with filtering septum; used in laboratory sampling.

filter-type respirator

A protective device that removes dispersoids from the air by physically trapping the particles on the fibrous material of the filter. It offers no protection against gases or vapors, or atmospheres deficient in oxygen. Many workers, however, are subjected to dusts, fumes, and mists in sufficient quantity to impair their health. Common examples are the dusts of cement, coal, flour, limestone, silica, and asbestos encountered in mining, grinding, and crushing operations; the metallic fumes of welding, smelting, and refining processes; and the mists formed by the disintegration of a liquid in such work as spray-coating, atomizing, and chromium-plating.


The liquid product from the filtration process.


Removal of suspended and/or colloidal material from a liquid by passing the suspension through a relatively fine porous medium, e.g., a canvas or other fabric diaphragm; the process is activated by suction or pressure, and commonly includes filter aids. The products are clear liquid and a filter cake.

filtration differentiation

See: filter pressing.

filtration rate

The measure of the amount of filtrate passing through or into a porous medium. Filter loss and cake thickness constitute the determining factors of filtration qualities.


Som. A local term for combustible gases.

final controlling element

In process control, the element that directly changes the value of the manipulated variable.

final exploration

The detailed investigation of a coal or mineral area on which a preliminary report was favorable. The final exploration of an area may involve a costly boring program, surveys, and sampling. See also: preliminary exploration.


a. Composed of or constituting relatively small particles; e.g., fine sandy loam. Ant. coarse.

b. Sometimes used to designate high-quality drill diamonds. c. A measure of the amount of gold in electrum.

fine aggregate

The portion of an aggregate consisting of particles with diameters smaller than approx. 1/4 in (4.8 mm). CF: aggregate; coarse aggregate.

fine gold

a. Almost pure gold. The value of bullion gold depends on its percentage of fineness. See also: fineness; float gold.

b. In placer mining, gold in exceedingly small particles. Syn: greasy gold.


a. Said of a crystalline rock, and of its texture, in which the individual minerals are relatively small; specif. said of an igneous rock whose particles have an average diameter less than 1 mm. Syn: aphanitic.

b. Said of a sediment or sedimentary rock, and of its texture, in which the individual constituents are too small to distinguish with the unaided eye; specif. said of a sediment or rock whose particles have an average diameter less than 1/16 mm (62 mu m, or silt size and smaller). The term is used in a relative sense, and various size limits have been used. CF: coarse-grained; medium-grained. c. Said of a soil in which silt and/or clay predominate.

fine-grained rocks

Rocks in which the crystals are very fine-grained, or else the whole or part is glass. These are the volcanic rocks.

fine grinder

A machine for the final stage of size reduction; i.e., to -100 mesh. See: fine grinding; pulverizer.

fine grinding

Fine grinding is usually performed in a mill rotating on a horizontal axis and containing balls, rods, or pebbles (grinding media), which serve to grind the ore in the mill. The different mills used in fine grinding are known as ball mill, pebble mill, Hardinge mill, tube mill, autogenous, etc.

fine industrials

See: toolstone.

fine metal

The higher grades of copper regulus or matte obtained in the English process of copper smelting. Included are the following four varieties, which are distinguished by appearance and copper content: (1) blue, containing about 60% copper; (2) sparkle, about 74% copper; (3) white, about 77% copper; and (4) pimple, about 79% copper.


a. The proportion of pure silver or gold in jewelry, bullion, or coins; often expressed in parts per thousand; American silver coin is nine-tenths or 0.900 fine; English gold coin is eleven-twelfths or 0.9166 fine.

b. A measure of specific surface area or particle-size distribution. c. The state of subdivision of a substance.

fineness factor

A measure of the average particle size of clay and ceramic material, computed by summing the products of the reciprocal of the size-grade midpoints and the weight percentage of material in each class (expressed as a decimal part of the total frequency). The measure is based on the assumption that the surface areas of two powders are inversely proportional to their average particle sizes. Syn: surface factor.

fineness modulus

a. A means of evaluating sand and gravel deposits, consisting of passing samples through standardized sets of sieves, accumulating percentages retained, dividing by 100, and comparing the resultant fineness-modulus number to various specification requirements.

b. An empirical factor obtained by adding the total percentages of a sample of the aggregate retained on each of a specified series of sieves, and dividing the sum by 100. c. One-hundredth of the sum of the cumulative values for the amount of material retained on the series of Tyler or U.S. sieves including half sizes up to 100 mesh.


a. Finely crushed or powdered material, e.g., of coal, crushed rock, or ore, as contrasted with the coarser fragments; esp. material smaller than the minimum specified size or grade, such as coal with a maximum particle size less than 3.2 mm, or ores too pulverulent to be smelted in the ordinary way; or material passing through a given screen or sieve.

b. An engineering term for the clay- and silt-sized soil particles (diameters less than 0.074 mm) passing U.S. standard sieve No. 200. c. See also: anthracite fines.

fine sand

a. A geologic term for a sand particle having a diameter in the range of 0.125 to 0.25 mm (125 to 250 mu m, or 3 to 2 phi units). Also, a loose aggregate of sand consisting of fine sand particles. See also: sand.

b. An engineering term for a sand particle having a diameter in the range of 0.074 mm (retained on U.S. standard sieve No. 200) to 0.42 mm (passing U.S. standard sieve No. 40). c. A soil term used in the United States for a sand particle having a diameter in the range of 0.10 to 0.25 mm.

fine silt

A geologic term for a silt particle having a diameter in the range of 1/128 to 1/64 mm (8 to 16 mu m, or 7 to 6 phi units). In Great Britain, the range 1/100 to 1/20 mm has been used. Also, a loose aggregate of silt consisting of fine silt particles.

fine silver

Pure silver, 1,000 parts fine or 100% silver.


a. One of the cutting edges on a finger bit. See also: finger bit.

b. A pair or set of bracketlike projections placed at a strategic point in a drill tripod or derrick, generally at a level with one of the work platforms, to keep a number of lengths of drill rods or casing in place when they are standing in the tripod or derrick. Also one of the flexible prong parts of a basket lifter. c. A minor structure radiating from a major structure.

finger bar

Pivoted length of wood used to support a unit in a stamp battery. See also: cam stick.

finger bit

A steel rock-cutting bit having fingerlike, fixed or replaceable, steel-cutting points affixed.

finger board

A board with projecting dowels or pipe fingers located in the upper part of the drill derrick or tripod to support stands of drill rod, drill pipe, or casing. CF: finger.

finger chute

Steel rails hinged independently over an ore chute, to control rate of flow of rock.

finger grip

A finishing tool designed to recover a broken drill rod or dropped tool from a borehole.

finger lifter

A basket-type core lifter.

finger raise

Steeply sloping openings permitting caved ore to flow down raises through grizzlies to chutes on the haulage level.

finished steel

Steel that has been processed beyond the stages of billets, blooms, sheet bars, slabs, and wire rods, and is ready for the market.

finish grade

The final grade required by specifications.

finishing jig

The jig used to save the smaller particles of ore in a concentrator.

finishing lime

A type of refined hydrated lime, which has been milled to be suitable for plastering, particularly a finish coat.

finishing rolls

The last roll, or the one that does the finest crushing in ore dressing, esp. in stage crushing.

fink truss

A frequently used symmetrical steel roof truss that is effective over a maximum span of 50 ft (15.2 m).


A hexagonal mineral, Pb (sub 5) (AsO (sub 3) ) (sub 3) Cl ; occurs as prisms forming crusts lining crevices in granular hematite at Laangban, Sweden.

fior di persicor

A white marble with veins and clouds of purple or red, from Albania.


Siliceous sinter, named from Mount Santa Fiora, Tuscany, Italy. Syn: pearl sinter.


a. To explode or blow up. The expression "the pit has fired" signifies that an explosion of combustible gases has taken place.

b. To blast or explode with ammonium nitrate-fuel oil (ANFO), dynamite, or other explosive. c. A word shouted by miners as warning just before a shot is fired. d. Fuel in a state of combustion, as on a hearth, in a grate, or furnace. A manifestation of rapid combustion or combination of materials with oxygen. e. Flashes of different spectral colors seen in diamonds and other gemstones with high birefringence as a result of dispersion. CF: play of color.

fire agate

See: goldstone.

fire assay

The assaying of metallic ores, usually gold and silver, by methods requiring a furnace heat; commonly involves the processes of scorification, cupellation, etc.


The back wall of a furnace or fireplace.

fire bank

The spoil heap at the surface of a colliery, when burning or heated by spontaneous combustion.


See: pyrostilpnite.

fire boss

a. A person designated to examine the mine for gas and other dangers. In certain states, the fire boss is designated as the mine examiner. See also: gasman.

b. A State-certified supervisory mine official who examines the mine for combustible gases and other dangers before a shift comes into it and who usually makes a second examination during the shift; in some States, it is used loosely to designate assistant or section foreman. See also: fireman. c. Also called examiner; mine examiner. See: gas watchman.


One of the small refractory-lined chambers, built wholly or partly in the wall of a kiln, for combustion of the fuel.


A strip across the area in which no combustible material is employed, or in which, if timber supports are used, sand (not waste rock) is later filled and packed tightly around them. Where timber is not used in stope supports, the firebreaks are simply stretches in the levels or winzes in which timber lagging is replaced by some other substance, such as steel or concrete.

fire breeding

S. Staff. Said of any place underground showing indications of a gob fire.


a. Bricks made from a very refractory clay to withstand intense heat.

b. An aluminosilicate brick of fire-clay composition.

fire bridge

The separating low wall between the fireplace and the hearth of a reverberatory furnace.

fire classification

The following explains the National Fire Protection Association classifications. Class A fires are defined as those in ordinary solid, combustible materials, such as coal, wood, rubber, textiles, paper, and rubbish. Class B fires are defined as those in flammable liquids, such as fuel or lubricating oils, grease, paint, varnish, and lacquer. Class C fires are defined as those in (live) electric equipment, such as oil-filled transformers, generators, motors, switch panels, circuit breakers, insulated electrical conductors, and other electrical devices.


a. A siliceous clay rich in hydrous aluminum silicates, capable of withstanding high temperatures without deforming, disintegrating, or becoming soft and pasty. It is deficient in iron, calcium, and alkalies, and approaches kaolin in composition, the better grades containing at least 35% alumina when fired.

b. A term formerly, but inaccurately, used for underclay. Although many fireclays commonly occur as underclays, not all fireclays carry a roof of coal and not all underclays are refractory. Syn: firestone; refractory clay. See also: sagger; underclay.


Eng. Said of a mine when an explosion of combustible gases has taken place.


a. A combustible gas that is formed in mines by decomposition of coal or other carbonaceous matter and that consists chiefly of methane; also the explosive mixture formed by this gas with air. The term "combustible gases" is now used for firedamp.

b. A stone, brick, or concrete airtight stopping to isolate an underground fire, and to prevent the inflow of fresh air and the outflow of foul air. See also: seal; methane.

fire door

a. A fireproof door in a building or in a mine, as a door to enclose an area in which there is a mine fire.

b. The door or opening through which fuel is supplied to a furnace or stove.

fired stone

Certain gems, e.g., zircon, topaz, or corundum, can be heated under controlled conditions to change their color to one that is more attractive. See also: heated stone.

fire feeder

a. An apparatus for feeding the fire of a furnace.

b. A stoker.

firefighting plan

A plan or chart showing the positions of items of firefighting equipment. Separate plans are used for surface buildings and underground workings.

fire grate

The grate that holds the fuel in many forms of heaters and furnaces.


Eng. Words marked upon the scale of a mercurial barometer to indicate when considerable combustible gases may be expected to be given off in the mine, and to show that extra vigilance is required to keep the ventilation up to its full strength.

fire kiln

An oven or place for heating anything.


a. In a metal mine, a miner whose duty it is to explode the charges of explosive used in headings and working places.

b. In a fiery mine, the official who checks the underground explosive risk. c. In a coal mine, an official responsible for safety conditions underground. See also: deputy. d. Eng. A person whose duty it is to examine with a safety lamp the underground workings, (1) to ascertain if gas is present, (2) to see that doors, bratticing, stoppings, etc., are in good order, and (3) generally to see that the ventilation is efficient. See also: fire boss; gas watchman.

fire marble

See: lumachelle.

fire opal

A transparent to translucent yellow, orange, red, or brown variety of opal that gives out fiery reflections in bright light with or without a play of color. CF: gold opal. Syn: sun opal; pyrophane.

fire-refined copper

Copper that has been refined by the use of a furnace process only, including refinery shapes and, by extension, fabricator's products made therefrom. Usually when this term is used alone, it refers to fire-refined, tough pitch copper without elements other than oxygen being present in significant amounts. See also: fire refining.

fire refining

Includes a number of processes used for the removal of impurities from impure metals produced by the smelting process. Impurities are removed by introducing air into the molten metal or exposing the metal to air, and by the addition of various fluxes and the removal of impurities as gases, drosses, or liquid slags. Lead, tin, and some types of impure copper are also fire-refined.

fire rib

S. Staff. A solid rib or wall of coal left between workings to confine gob fires.

fire runner

In bituminous coal mining, a person who enters a mine immediately after blasting to search for any fires that might have been started by a blast. Also called shotfirer runner; shot runner.

fire sand

a. Refractory oxide or carbide used for furnace linings.

b. A sand so free from fluxes that it is highly refractory. See also: foundry sand.

fire seal

A strip across an area through which neither fire nor noxious gases can penetrate. It involves not only sealing of stopes but levels also. Syn: sealing.

fire setting

An ancient method of tunneling through rock. A fire was built against the face of the mineral, which was then quenched with water, thus causing cracking.

fire stink

The smell given off when heating or spontaneous combustion occurs in the waste or elsewhere underground.


a. Any fine-grained siliceous stone formerly used for striking fire; specif. flint. Syn: feverstein.

b. A nodule of pyrite formerly used for striking fire. c. A fine-grained siliceous rock that can resist or endure high heat and is used for lining furnaces and kilns, such as certain Cretaceous and Jurassic sandstones in southern England. See also: fireclay. d. In a slag hearth, a plate of iron covering the front of the furnace except for a few inches of space between it and the bedplate. e. Quartz in which cracks have been artificially produced by heating to create diffraction colors. Syn: iris quartz.

fire styth

See: fire stink.

fire up

A command to start operating a drill either to collar a borehole or to restart work on the first working shift of a day.


a. The igniting of an explosive charge.

b. Starting up a furnace or kiln. c. The process of initiating the action of an explosive charge or the operation of a mechanism that results in a blasting action.

firing a mine

Eng. Maliciously setting fire to a coal mine.

firing cable

See: shot-firing cable.

firing circuit

See: shot-firing circuit.

firing current

An electric current of recommended magnitude and duration to sufficiently energize an electric detonator or a circuit of electric detonators.

firing expansion

The increase in size that sometimes occurs when a refractory raw material or product is fired; it is usually expressed as a linear percentage expansion from the dry to the fired state. Firing expansion can be caused by a crystalline conversion (e.g., of quartz into cristobalite, or of kyanite into mullite plus cristobalite), or by bloating.

firing impulse

As applied to electric blasting caps, the minimum impulse of current required to fire a detonator.

firing key

A special key that fits the exploder used in electric firing of blasting charges; carried by authorized shot firer.

firing line

Scot. An appliance used in former times for clearing a room of combustible gases. A prop was being set up near the face, a ring was fixed in it near the roof, and a cord or wire was passed through the ring. Attaching a lamp to one end of the cord, the miner withdrew to a distance, and by pulling the cord raised the lamp to the height necessary to explode the accumulated combustible gases.

firing machine

a. A designation for an electric blasting machine.

b. An apparatus for feeding a boiler furnace with coal. A mechanical stoker.

firing point

Eng. The point or mixture at which combustible gases mixed with atmospheric air explodes. The percentages of gas vary from 6% to 13%, with the maximum explosibility at about 11%.

firmament stone

See: precious opal.

first aid

Emergency, crude repair of a bit made by a drill runner at the drill site.

first arrival

The first energy to arrive from a seismic source. First arrivals on reflection records are used for information about a surficial low-velocity or weathering layer; refraction studies are often based on first arrivals. Syn: initial impulse; first break.

first break

See: weight break; first arrival.

first bye

a. A diamond with a faint greenish tint.

b. A classification of gem diamond.

first-class lever

A bar having a fulcrum (pivot point) between the points where force is applied and where it is exerted.

first-class ore

An ore of sufficiently high grade to be acceptable for shipment to market without preliminary treatment. CF: second-class ore. Syn: shipping ore.

first mining

In the room-and-pillar method, the part of the coal that is won from the rooms, as distinguished from the second part, which is the extraction of the remaining pillars.

first-order red plate

See: selenite plate.

first ripping

See: gypsum plate.
The ripping work carried out as the roadway is being formed and driven forward. See also: second ripping.

first water

Gems, particularly diamonds, of the highest value, irrespective of size. In diamonds, the term applies to stones that are flawless, without color or almost bluish white. A slight amount of color detracts from the value, and the stones are said to be off color.

first way

Rift; reed; cleavage way. See also: easy way.

first weight

The first indication of roof pressure that takes place after the removal of coal from a seam.

first working

The removal of the coal in driving the entries and rooms. See also: advance working. CF: second working.


A long, narrow arm of the sea; also, the opening of a river into the sea. Along the Scottish coast, it is usually the lower part of an estuary (e.g., Firth of Forth), but sometimes it is a fjord (e.g., Firth of Lorne) or a strait (e.g., Pentland Firth). Etymol. Scottish. Syn: frith.

fir-tree bit

A rotary bit in which a number of cutting edges are arranged behind a pilot bit to enlarge the hole to the required diameter.

Fischer-Tropsch process

Hydrogenation of carbon monoxide to form hydrocarbons from coal or natural gases.


a. To join two beams, rails, etc., by long pieces at their sides.

b. The article recovered and/or the act or processes involved in the recovery of lost drilling tools, casing, or other articles from a borehole. Also called fishing.

fished joint

A rail joint made by means of fishplates.

Fisher subsieve sizer

An apparatus using a gas-permeability method for determination of the average particle diameter of powders. A sample, equal in weight (grams) to the true density of the material, is compacted between two porous plugs in a metal tube, to a known porosity. Air or a suitable gas, under a constant pressure head, is passed through the compressed sample, and rate of flow is measured by a calibrated flowmeter. The average particle diameter of the powder is indicated directly on a self-calculating chart by the liquid height in one arm of the flowmeter tube. No dispersion is required, and the results are unaffected by particle shape.


a. A little-used name for moonstone, also for opal with a girasol effect.

b. A popular trade term for any transparent faceted stone so cut that its center is lacking in brilliancy. c. A diamond cut too thin to present the maximum effect of brilliancy.

fisheye stone

See: apophyllite.


Searching for and attempting to recover, by the use of specially prepared tools, a piece or pieces of drilling equipment (such as sections of pipe, cables, or casting) that have become detached, broken, or lost from the drill string or have been accidentally dropped into the hole.

fishing tap

A thread-cutting tool to cut threads inside a casing or other hollow part that is to be fished from a borehole.


Specially shaped steel plates for joining the end of one rail to the next rail in the track. The fishplates are fixed (one on each side) to overlap the rail ends and bolted through the rails.


a. An abrupt and ragged termination of a coalbed that is considered to have resulted from a washout during the peat stage. The more or less leathery peat is believed to have been separated parallel to its bedding, permitting wedges of sand and silt to be forced into the separations in such a manner that, after the coalification has taken place, a cross section shows splayed and ragged coal separated by sandstone wedges.

b. The act or process of rotatively drilling a borehole with a fishtail bit. Also called fishtailing. c. In roll forging, the excess trailing end of a forging. It is often used, before being trimmed off, as a tong hold for a subsequent forging operation.

fishtail bit

A rotary bit used to drill soft formations. The blade is flattened and divided, the divided ends curving away from the direction of rotation. It resembles a fishtail. Also called drag bit. CF: noncoring bit.

fishtail structure

A coal seam structure sometimes observed along the fringe of a washout. It was probably produced by the water forcing open layers of the coaly mass and the injection of fine sand or silt into the splayed partings--the veins of coal branching out like a fishtail.


a. Capable of being easily split along closely spaced planes; exhibiting fissility.

b. Said of bedding that consists of laminae less than 2 mm thick.


A general term for the property possessed by some rocks of splitting easily into thin layers along closely spaced, roughly planar, and approx. parallel surfaces, such as bedding planes in shale or cleavage planes in schist; its presence distinguishes shale from mudstone. The term includes such phenomena as "bedding fissility" and "fracture cleavage." Etymol. Latin fissilis, that which can be cleft or split. Adj. fissile.


The spontaneous or induced splitting, by particle collision, of a heavy nucleus into a pair (only rarely more) of nearly equal fission fragments plus some neutrons. Fission is accompanied by the release of a large amount of energy. CF: fusion.


Said of nuclei, such as uranium and plutonium, that are capable of fission.


A fracture or crack in rock along which there is a distinct separation. It is often filled with mineral-bearing material. See also: fissure vein.

fissure system

A group of fissures of the same age and of more or less parallel strike and dip.

fissure vein

A mineral mass, tabular in form as a whole but frequently irregular in detail, occupying a fracture in rock. The vein material is different from the country rock and has generally been produced by the filling of open spaces along the fissure. See also: true vein.


Said of a drill hold sufficiently crooked to make a drill stick.


Broadly, a skilled person who can repair and assemble machines in an engineering shop.


Hand or bench work involved in the assembly of finished parts by a fitter.


Auxiliary and accessory tools and equipment needed to drill a borehole using either percussive, churn, rotary, diamond, or other types of drills.


a. A twinned crystal formed by fivefold cyclic twinning.

b. A crystal twin consisting of five individuals. CF: trilling; fourling; eightling.


a. A position determined from terrestrial, electronic, or astronomical data.

b. The act of determining a fix. c. To fettle or line the hearth of puddling furnace with a fix or fettling, consisting of ores, scrap, and cinder, or other suitable substances.


a. The act or process by which a fluid or a gas becomes or is rendered firm or stable in consistency, and evaporation or volatilization is prevented. Specif., that process by which a gaseous body becomes fixed or solid on uniting with a solid body, as the fixation of oxygen or the fixation of nitrogen.

b. A state of nonvolatility or the process of entering such a state, as the fixation of a metal or the fixation of nitrogen in a nitrate by bacteria.


A group name for all authigenic, nonfluid bitumens; divided into stabile protobitumens and metabitumens.

fixed carbon

a. In the case of coal, coke, and other bituminous materials, the solid residue, other than ash, obtained by destructive distillation; determined by definite prescribed methods.

b. A calculated figure: 100, less the sum of the percentages of moisture, volatile matter, and ash.

fixed-clip monocable

An aerial ropeway in which a moving endless rope both supports and transports carriers that are permanently fixed to it. The length of the line may be several miles. Individual loads are limited to about 2 hundredweight (91 kg), and total capacity seldom exceeds about 15 st/h (13.6 t/h).

fixed-electrode method

A geophysical surveying method used in the self-potential system of prospecting, in which one electrode remains stationary while the other is grounded at progressively greater distances from it. The method indicates a mineral body directly beneath the greatest anomaly and has been extensively and successfully used.

fixed-flexible-type carrying idler

Consists of a flexible-type carrying idler mounted in a rigid frame, which fixes the position of the points or roll support.

fixed ground water

Ground water in material having interstices so small that the water is held permanently to the walls of the interstices, or moves so slowly that it is not available for withdrawal at useful rates. Outside the zone of saturation, material with infinitely small openings can hold water indefinitely against the pull of gravity, whereas within the zone of saturation there is apparently always movement, even though at very low rates.

fixed guides

Wood bars or steel rails fixed vertically to cross buntons in a shaft. The cage shoes travel along the guides and therefore prevent the cage from swinging and doing damage in the shaft. Some skips are fitted with rubber-tired rollers running on 6-in by 4-in (15-cm by 10-cm) steel channel guides. Guide shoes may be fitted to act as alternative guides in case of breakdown of rollers. Fixed guides are used when shaft space is limited; i.e., when the clearances do not permit the use of flexible or rope guides. See also: steel guides.

fixed screen

A stationary inclined or curved panel, commonly made of wedgewire, which is used to remove fines and a large proportion of water from a suspension of coal in water.


A monoclinic mineral, Pb (sub 14) Ag (sub 5) Sb (sub 21) S (sub 48) (?) ; soft; forms deeply striated prisms at Kisbanya, Romania, where it is associated with semseyite, pyrite, galena, and sphalerite.


a. Sandstone or sandy limestone rock, usually more or less micaceous, which is fissile along the bedding planes, splitting into slabs. Sometimes misnamed "slate" because it is used for roofing rather than paving.

b. A thin slab of stone. Syn: flagstone. c. A track signal or target.


In bituminous coal mining, a laborer who attaches a flag to the rear car of a loaded train of cars (if the flag is missing at end of a haulage trip, it denotes that the train has lost one or more cars, and all motormen are warned). Also called flagman.


In geophysical work, the use by surveyors of flags of cloth, paper, or plastic to mark instrument or shot locations.


a. Splitting or tending to split into layers of suitable thickness for use as flagstones; specif. descriptive of a sedimentary rock that splits into layers from 1 to 5 cm thick (McKee &Weir, 1953).

b. Said of bedding that consists of layers from 1 to 10 cm thick (Payne, 1942). c. Pertaining to a flag or flagstone. d. Said of a soil full of flagstone fragments.


An orthorhombic mineral, C (sub 10) H (sub 22) O (sub 3) , cis-terpin hydrate; forms colorless transparent crystals in fossil pine logs near the San Francisco Peaks, north of Flagstaff, AZ.


a. A hard sandstone, usually micaceous and fine-grained, that occurs in extensive thin beds with shale partings; it splits uniformly along bedding planes into thin slabs suitable for use in terrace floors, retaining walls, etc. CF: bluestone; freestone.

b. A flat slab of flagstone used for paving; esp. a thin piece split from flagstone. Also, a surface of such stone. c. A relatively thin flat fragment (of limestone, sandstone, shale, slate, or schist) occurring in the soil, having a length in the range of 6 to 15 in (15 to 38 cm). Syn: flag; slabstone; grayband.


A hammer hinged to an axle so that it can be used to break or crush material.

flake copper

Very thin scales of native copper.

flake graphite

Graphite disseminated in metamorphic rock as thin, visible flakes that are separable from the rock by mechanical means. Syn: crystalline flake graphite.

flake mica

Finely divided mica recovered from mica and sericite schist and as a byproduct of feldspar and kaolin beneficiation. See also: scrap mica.

flake sulfur

Pyrite occurring as thin flakes on the natural cleavage surfaces of coal that floats readily on the surface of the wash water in the washing process. Syn: float sulfur.

flake white

A name sometimes given to pure white lead.

flamboyant structure

The optical continuity of crystals or grains, as disturbed by a divergent structure caused by slight differences in orientation.


A burning mixture of a combustible gas (or vapor) and air. Solid fuels burn with a glow, but with little flame. Flames are normally hot, but under some conditions are relatively cool. Principal types of flame are luminous, nonluminous, long (lazy) flames, and short flames.

flame-coloration tests

In mineral identification, qualitative tests made by moistening powdered material with hydrochloric acid, placing a few grains on platinum or nickel-chrome wire, and noting any color imparted to a blue Bunsen flame. Sodium gives a strong yellow flame; calcium, light red; strontium, crimson; barium, green; potassium, lilac; and copper, blue-green.

flame drill method

See: jet piercing.

flame emission spectrometry

See: flame photometry.

flame hardening

A method for local hardening in which the steel is heated by a mechanically operated oxyacetylene blowpipe, which traverses the object to be hardened at a predetermined rate.

flame inhibitor

A substance, such as hexachloroethane, used for coating limestone dust for use in stone-dust barriers. The inhibitor is dissolved in the waterproofing agent. Tests have indicated its effectiveness in preventing or reducing the propagation of coal-dust explosions. See also: stone-dust barrier.

flame kiln

A lime kiln burning wood.

flame opal

a. Opal in which red play of color occurs in more or less irregular streaks.

b. A flash opal with red as the predominant color.

flame photometry

Measurement of the intensity of the lines in a flame spectrum by a flame photometer. Syn: flame emission spectrometry.


A term descriptive of electrical machines, switches, and fittings demanded legally for use in fiery mines in Great Britain. Enclosing boxes with accurately fitted wide flanges are used. See also: explosion proof.

flameproof construction

A flameproof enclosure for electrical apparatus is one that, under normal working conditions, will withstand the internal explosion of a flammable gas that may exist within it, and which will prevent the transmission of a flame capable of igniting an explosive atmosphere outside the equipment.

flameproof enclosure

An enclosure for electrical apparatus that will withstand, without injury, any explosion of the prescribed flammable gas that may occur within it under practical conditions of operation within the rating of the apparatus (and recognized overloads, if any, associated therewith), and will prevent the transmission of flame such as will ignite the prescribed flammable gas that may be present in the surrounding atmosphere.

flame recorder

See: photographic-paper recorder.

flame-resistant cable

A portable cable that will meet the flame test requirements of the U.S. Mine Safety and Health Administration.

flame safety lamp

A lamp, the flame of which is so protected that it will not immediately ignite combustible gases. The original flame safety lamp was developed by Sir Humphrey Davy in 1815 and there are several varieties. The flame is generally surrounded by a cylindrical covering of wire gauze. An explosive or flammable mixture of gas entering the lamp will be ignited by the flame, but the flame of combustion will not pass through the cool gauze and ignite the gas outside the lamp. The illuminating power of these lamps is slightly more than 1 cd, and they will burn for an entire shift with one filling. Each lamp is generally provided with a relighting device, and with a magnetic lock to prevent the lamp from being opened in the mine. The chief disadvantage of this lamp is its low illuminating power. See also: Davy lamp; safety lamp; electric cap lamp.

flame spectrum

The spectrum of light emitted by a substance by heating it in a flame.

flame spinel

Intensely bright orange-red rubicelle (spinel).

flame spread index

The numerical designation that indicates the surface flammability of materials as specified by the ASTM E-162 test method "Surface Flammability of Materials Using a Radiant Heat Energy Source." U.S. Federal regulations require a flame spread index of 25 or less for flame-retardant coatings and sealants used in underground mines.

flame test

A qualitative analysis of a mineral made by intensely heating a powdered or dissolved sample in a flame and observing the flame's color, which is indicative of the element involved; e.g., green from copper. CF: flame photometry.


Capable of being easily ignited and of burning with extreme rapidity. This adj. is now used technically in preference to inflammable because of the possible ambiguity of the "in" prefix. Certain equipment cannot be used for safety reasons in coal mines in which flammable gases are present.

flammable fringe

In a system where air (or other reactant gas) and a flammable gas are present, that region in which the two gases have mixed to produce a gas capable of propagating flame.

flammable mixture of gases

A mixture that when once ignited, will allow flame to be self-propagated throughout the mixture, independent of and away from the source of ignition. In coal mines, it is only when methane and air are mixed in certain definite proportions that the mixture is flammable and explosive, and will allow flame to spread in all directions. See also: limits of flammability.


Derb. Clay ironstone in beds or seams.

flamrich screen

See also: resonance screen.


Applied to a vein widening.

flange wheel

A truck or trolley wheel having a flange or flanges at the edge to keep it from leaving the rail.


A syn. for limb of a fold.

flank hole

a. A hole bored ahead of a working place, when approaching old workings.

b. A borehole to detect water, gas, or other danger, driven from the side of an underground excavation in a line not parallel with the centerline of the excavation. Also called flank bore; flanking hole.

flanking hole

A shothole drilled at an acute angle to the coal face for the purpose of trimming it.

flanking hole method

Holes bored into the face at an angle which may vary from 30 degrees to 60 degrees to the line of face and 6 to 7 ft (1.8 to 2.1 m) long. The distance between shot holes, the angle of the hole, and the charge, depend to a great extent on the hardness of the coal. As the coal grows harder, the burden on each shothole must be reduced by placing the shotholes closer together and reducing the angle of the hole to the face.


a. See: clack.

b. The hinged, flat disk mounted inside the lower end of a core barrel that closes and holds the sample when the barrel is withdrawn from a boring.


A laborer who flattens copper starting sheets by beating them against a rigid steel or copperplate with a wooden paddle to remove folds, buckles, and creases, which tend to cause short circuits during electrolytic copper refining. Syn: clack.

flapper-topped air crossing

Eng. An air crossing fitted with a double door or valve giving direct communication between the two air currents when forced open by the blast of an explosion.


a. Striking through the slag-covered surface of molten copper with a rabble blade just before the bath is poled to hasten oxidation.

b. Striking the surface of molten copper with an iron scraper or rabble to increase the surface exposed to the air.


Eng. Rectangular wooden valves about 24 in by 18 in by 1-1/2 in (61 cm by 46 cm by 3.8 cm) thick, hung vertically to the framework of the air chambers of a ventilator. A flap valve.

flap valve

Nonreturn valve formed by a hinged flap, which rises as fluid is drawn up through a pipe or chamber and falls back on seating to prevent return flow.

flare-type bucket

A dragline bucket with a bowl of aluminum alloy covered top and bottom with steel wearing plates. Sides and back are of steel plates, and manganese steel is used for the lip and teeth. This bucket has no arch; thus weight is minimized. The sides are flared, permitting heaped loading, and the bucket dumps backward, not forward, thereby giving a somewhat longer dumping range.

flaser gabbro

Coarse-grained blastomylonite formed by dislocation metamorphism of a gabbro. Flakes of mica or chlorite sweep around augen of feldspar and/or quartz with much recrystallization and neomineralization. See also: mylonite gneiss.

flaser structure

A structure in dynamically metamorphosed rock in which lenses and layers of original or relatively unaltered granular minerals are surrounded by a matrix of highly sheared and crushed material, giving the appearance of a crude flow structure; e.g., flaser gabbro. CF: augen structure.

flash box

A box in which a light source, an electromagnet, and a telescope are all mounted in the pendulum apparatus of gravitational recording.

flash coal dryer

An appliance in which the moist coal is fed into a column of upward-flowing hot gases and moisture removal is virtually instantaneous. Suspension dryers were widely used in the United States for drying coals from 1/2 in (1.3 cm) downwards in size. See also: Cascade coal dryer; Raymond flash dryer; suspension dryer; thermal drying.


Shallow lakes created by the removal of coal.

flash flood

A local and sudden flood or torrent of relatively great volume and short duration, overflowing a stream channel in a usually dry valley (as in a semiarid area), carrying an immense load of mud and rock fragments, and generally resulting from a rare and brief but heavy rainfall over a relatively small area having steep slopes. It may also be caused by ice jams and by dam failure. See also: freshet.

flash opal

a. An opal in which the play of color is limited to a single hue.

b. Opal in which the play of color is pronounced in one direction only.

flash over

a. Sympathetic detonation between explosive charges or between charged blast holes.

b. The transmission of detonation from a cartridge to another one in line; also, the tendency of a blast hole to be detonated by the shock wave from an adjacent borehole. Syn: sympathetic detonation.


The minimum temperature at which sufficient vapor is released by a liquid or solid to form a flammable vapor-air mixture at atmospheric pressure.

flash roast

Rapid removal of sulfur, as finely divided sulfide mineral is allowed to fall through a heated oxidizing atmosphere. Flash roasting or melting is widely used in the copper industry.

flash smelting

A smelting process in which dried metal sulfide concentrates are blown with oxygen or oxygen-rich air in a hot hearth-type furnace such that the particles react rapidly with the oxygen to generate a large amount of heat, partially (controlled) oxidizing the concentrates and producing a molten matte phase containing the metal values, which will be further processed, and a molten slag.


a. In foundry work, a molding box that holds the sand into which molten metal is poured. The top half or part is its cope, the bottom half is its drag, and it is furnished with locating lugs.

b. An iron bottle in which mercury is marketed. It contains 76-1/2 lb (41.3 kg). c. A tinned vessel in which a miner carries oil for a lamp or beverage for a lunch. d. A necked vessel for holding liquids; esp., a broad, flattened vessel of metal or sometimes glass.


a. In mine timbering, horizontal crosspiece or cap used in roof support.

b. Of a mining lode, one less than 15 degrees from horizontal in its dip. c. A horizontal orebody, regardless of genetic type. d. A flat coal seam. e. A railroad car of the gondola type for shipping coal. f. A dull diamond bit. See also: going bord.

flat arch

a. An arch in that both outer and inner surfaces are horizontal planes.

b. In furnace construction, a flat structure spanning an opening and supported by abutments at its extremities; the arch is formed by a number of specially tapered bricks, and the brick assembly is held in place by their keying action. Also called a jack arch.

flat belt conveyor

supported by flat belt idlers or by a flat surface.

flat belt idler

An idler consisting of one or more rolls supporting the belt in a flat position.

flat cut

A manner of placing the boreholes, for the first shot in a tunnel, in which they are started about 2 to 3 ft (0.6 to 0.9 m) above the floor and pointed downward so that the bottom of the hole is about level with the floor.

flat double cabochon

See: lentil.

flat drill

A rotary end-cutting tool constructed from a flat piece of material provided with suitable cutting lips at the cutting end.

flat ends

Thin cleavages from the faces of a diamond crystal.

flat hole

A borehole following a near horizontal course.

flat idler

A belt idler that supports the belt in a flat position.


One of a series of short, triangular hogbacks forming a spur or ridge on the flank of a mountain, having a narrow apex and a broad base, resembling (when viewed from the side) a huge flatiron; it usually consists of a plate of steeply inclined resistant rock on the dip slope.

flat joint

In igneous rock, a joint dipping at an angle of 45 degrees or less. Rarely applied to joints dipping more than 20 degrees .

flat lode

A lode which varies in inclination from the horizontal to about 15 degrees.

flatnose shell

A cylindrical tool with a valve at the bottom, for boring through soft clay.

flat rods

A series of horizontal or inclined connecting rods, running up upon rollers, or supported at their joints by rocking arms, to convey motion from a steam engine or water wheel to pump rods at a distance.

flat rope

A steel rope made up of a number of loosely twisted four-strand ropes placed side by side, the lay of the adjacent strands being in opposite directions to secure uniformity in wear and to prevent twisting during winding. The strands are sewn together with steel wire.


a. Subterraneous beds or sheets of traprock or whin.

b. Narrow decomposed parts of limestones that are mineralized.

flats and pitches

a. A phrase descriptive of the structure of the lead and zinc deposits in dolomite of the Upper Mississippi Valley region of the United States, esp. in Wisconsin. The flats are nearly horizontal solution openings; the pitches are the inclined, interconnecting joints.

b. A slump structure of both horizontal and steeply inclined cracks in sedimentary strata. Syn: pitches and flats.

flat sheet

a. A steel plate laid on the floor at the face of a tunnel or heading before blasting to provide a smooth floor for shoveling the broken rock into tubs. Syn: turnsheet.

b. Blanket deposit.

flattened strand rope

A wire rope designed to give a greater wearing surface than ordinary round ropes and yet have about the same strength and flexibility. They have roughly 50% more wearing surface than ordinary round ropes, owing to the Lang lay of wires. See also: wire rope.


a. York. Horizontal vein of spar or barytes in the lead mines. Also called flatting bed.

b. A process for truing-up handmade fireclay refractories while they are still only partially dry. Handmaking is now little used except for some special shapes.


Scot. A working of moderate inclination. See also: flat; flat lode.


a. A general term for any internal or external imperfection of a fashioned diamond or other gemstone. It includes cracks, inclusions, visibly imperfect crystallization, internal twinning, and cleavage.

b. An old term for a steep, transverse strike-slip fault.


Said of a diamond or other gemstone that is free from flaws of any description when observed by a trained eye under efficient illumination with a fully corrected magnifier of not less than 10 power.

flaxseed ore

An iron-bearing sedimentary deposit, e.g., the Clinton ore, composed of disk-shaped hematitic oolites that have been somewhat flattened parallel to the bedding plane. CF: fossil ore.