Appendix:Dictionary of Mining, Mineral, and Related Terms/F/4

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A portion of an unconsolidated sediment or of a crushed consolidated rock sample or of a crushed ore or mineral sample that has been separated by some method, and is distinguished in some manner from all the other portions (or fractions) comprising the whole sample being analyzed. Also a fraction may be separated and defined on the basis of its mineral content, its specific gravity or density, its magnetism or lack of magnetism, or its solubility or insolubility in acid.

fractional crystallization

a. Crystallization in which the early-formed crystals are prevented from equilibrating with the liquid from which they grew, resulting in a series of residual liquids of more extreme compositions than would have resulted from equilibrium crystallization. CF: crystallization differentiation. Syn: fractionation.

b. Controlled precipitation from a saline solution of salts of different solubilities, as affected by varying temperatures or by the presence of other salts in solution.

fractional distillation

A distillation process for the separation of the various components of liquid mixtures. An effective separation can only be achieved by the use of fractionating columns attached to the still.

fractional shoveling

A method of sampling sometimes used at points where coal or mineral is loaded or unloaded by shoveling. Every tenth (or other number) shovelful is deposited separately as sampling material.

fractionating column

An apparatus for separating the high-boiling and low-boiling fractions of a substance, whereby the fractions with the lowest boiling point distill over. The efficiency depends on the column length and on the number of bubble plates used.


a. The separation of (1) a substance from a mixture, such as the separation of one isotope from another of the same element; (2) one mineral or group of minerals from a mixture; or (3) one size fraction from a mixture.

b. Separation of chemical elements in nature, by processes such as preferential concentration of an element in a mineral during magmatic crystallization, or differential solubility during rock weathering. See: fractional crystallization.


The study of the surfaces of fractures, esp. microscopic study.


a. A general term for any break in a rock, whether or not it causes displacement, due to mechanical failure by stress. Fracture includes cracks, joints, and faults.

b. The breaking of a mineral other than along planes of cleavage or parting. A mineral can be described in part by its characteristic fracture; e.g., uneven, fibrous, conchoidal, or hackly. CF: parting; uneven fracture. c. Deformation due to a momentary loss of cohesion or loss of resistance to differential stress and a release of stored elastic energy. CF: flow. Syn: rupture.

fracture cleavage

A type of cleavage that occurs in deformed but only slightly metamorphosed rocks and that is based on closely spaced, parallel joints and fractures. CF: flow cleavage.

fractured formation

See: fractured ground.

fractured ground

Rock formation shattered and crisscrossed with fissures and fractures. CF: broken ground.

fracture dome

The fracture dome is the zone of loose or semiloose rock which exists in the immediate hanging or footwall of a stope. In some mines it may extend into the walls for a considerable distance. In a rock burst it becomes greatly extended.

fracture porosity

Porosity resulting from the presence of openings produced by the breaking or shattering of an otherwise less pervious rock.

fracture stress

The differential stress at the moment of fracture. Syn: breaking stress.

fracture system

A set or group of contemporaneous fractures related by stress.


a. A rock or mineral particle larger than a grain.

b. A piece of rock that has been detached or broken from a preexisting mass; e.g., a clast produced by volcanic, dynamic, or weathering processes.


Formed from fragments of preexisting rocks. See also: clastic.

fragmental rock

See: clastic rock.

fragmental texture

a. A general textural term applied to rocks composed of fine materials or of sandy, conglomeratic, bouldery, and brecciated materials. The texture of clastic rocks.

b. A texture of sedimentary rocks, characterized by broken, abraded, or irregular particles in surface contact, and resulting from the physical transport and deposition of such particles; the texture of a clastic rock. The term is used in distinction to a crystalline texture. c. The texture of a pyroclastic rock, such as a tuff or volcanic breccia.


a. The breakage of rock during blasting in which explosive energy fractures the solid mass into pieces; the distribution of rock particle sizes after blasting. See also: degradation.

b. Index of the degree of breaking up of rock after blasting.

framboidal texture

A texture in which pellets form spheroidal aggregates resembling a raspberry.


a. In trench excavations requiring timbering, the struts separating the boards, together with the walings, which they hold, form a frame.

b. Eng. A table composed of boards slightly inclined, over which runs a small stream of water to wash off waste from slime tin; a buddle. Also called rack.

frame dam

Eng. A solid, watertight stopping or dam in a mine to keep back and resist the pressure of a heavy head of water.

framed dam

A barrier, generally built of timber framed to form a water face, supported by struts.

frame set

The legs and cap or crossbar arranged so as to support the roof of an underground passage. Also called framing; set.


A variety of black bort from South Africa showing minute brilliant points possibly due to included diamonds. CF: bort.

framing table

An inclined table used in separating ore slimes by running water; a miner's frame.

France screen

A traveling-belt screen in which the screen cloth is mounted on a series of separate pallets, thus avoiding bending the screen as it goes over the pulleys.


An orthorhombic mineral, (Ba,Pb)(UO (sub 2) ) (sub 2) (VO (sub 4) ) (sub 2) .5H (sub 2) O ; forms a series with curienite; occurs as yellow impregnations in sandstone; from Franceville, Gabon.

Franciscan Complex

Jurassic to Early Cretaceous rocks, characteristic of the Pacific coastal ranges of California, composed primarily of sandstones, cherts, serpentinites, and glaucophane schists. The Franciscan should not be visualized as a formation or sequence with ordinary physical, spatial, and temporal coherence, but rather as a disorderly assemblage of various characteristic rocks that have undergone unsystematic disturbance; a melange. The formation includes deep-water sediments and mafic marine volcanic material, locally accompanied by masses of serpentinite.

Francisci furnace

A furnace for the treatment of roasted blende and other fine ore. It consists of a series of superimposed muffles formed by arches of magnesia brick and built into the walls of the furnace and communicating with a common condensation chamber.


A triclinic mineral, (Pb,Sn) (sub 6) FeSn (sub 2) Sb (sub 2) S (sub 14) ; forms imperfect, radiated folia. Occurs at Poopo, Llallagua, and several other tin districts of Bolivia; at Coal River, UT; in Canada; and in Inyo and Santa Cruz Counties, CA.

Francois sinking process

The cementation sinking method. The process was introduced into Great Britain in 1911. See also: cementation sinking.


An isometric mineral, BaF (sub 2) ; fluorite group.


An isometric mineral, 8[ZnFe (sub 2) O (sub 4) ] ; magnetite series; spinel group; forms metallic black octahedra with rounded edges; weakly ferrimagnetic; a source of zinc at the Franklin and the Sterling Hill deposits, NJ.

Frasch process

a. A process for mining native sulfur, in which superheated water is forced into the deposits for the purpose of melting the sulfur. The molten sulfur is then pumped to the surface.

b. A desulfurizing process that consists of distilling oil over lead oxide, followed by refining with sulfuric acid. See also: sulfur mining.

Frasch sulfur

Native sulfur mined by the Frasch hot-water process.

Fraser's air-sand process

A dense-media process in which a dry, specific-gravity separation of coal from refuse is achieved by utilizing a flowing dense medium intermediate in density between coal and refuse. The dense medium is formed by bubbling air through a mass of dry sand, 30 to 80 mesh in size. The air dilates and fluidizes the sand mass, causing it to behave somewhat as a heavy liquid. The coal floats on the aerated sand mass and the refuse sinks. Syn: air-sand process.

Fraunhofer lines

Dark lines in the solar spectrum resulting from absorption of light by chemical elements in the chromosphere.

frautschy bottle

This water-sampling device is messenger actuated. It is designed to allow free flow while in the cocked position on the downward traverse. When the desired sampling point has been reached, the closures are messenger actuated, resulting in isolation of the sample on the return traverse. Frautschy bottles may be attached to the hydrographic wire at intervals and in such a manner that release of a single messenger from the surface will actuate the entire series. In this way samples from several depths may be obtained in a single operation.


A hexagonal mineral, CoSe ; nickeline group; in trace amounts with clausthalite, trogtalite, and hastite in dolomite veinlets in the Trogtal quarries, Harz Mountains, Germany.


a. Native; uncombined with other elements, such as free gold or free silver (native gold or native silver).

b. Chemically uncombined or readily obtainable in uncombined form by heating, as opposed to bound; e.g., free water or free oxygen.

free acidity

Free acidity is considered to be the portion of the total acidity that exists in the form of acid, both ionized and un-ionized.

free air

a. Air under conditions of atmospheric pressure and temperature. The condition of the air at the intake of the compressor, whatever the temperature and barometric pressure may be.

b. The total area of open space in a grille through which air can pass.

free-air anomaly

A gravity anomaly calculated from a theoretical model and elevation above sea level, but without allowance for the attractive effect of topography and isostatic compensation. See also: anomaly.

free-air correction

a. See: free-air anomaly.

b. A correction for the elevation of a gravity measurement, required because the measurement was made at a different distance from the center of the Earth than the datum. The first term of the free-air correction is 0.09406 mgal/ft (0.3086 mgal/m).

free-burning coal

a. A bituminous coal having so little fusibility that enough air for rapid combustion can flow between the lumps and high enough in volatiles and fixed carbon to burn readily.

b. Coal that does not cake in the fuel bed and which has a high volatile matter.

free cementite

Iron carbide in cast iron or steel other than that associated with ferrite in pearlite.

free chalk

Eng. A variety of soft marly chalk; Sussex.

free circulation

The circulation of a drilling fluid, the flow of which is not restricted by obstructing materials in the borehole or inside the drill string.

free crushing

Crushing under conditions of speed and feed such that there is plenty of room for the fine ore to drop away from the coarser part and thereby escape further fine crushing. CF: choke crushing.

free cyanide

The cyanide not combined in complex ions.

free-drainage level

An adit. A level that drains through an adit.

free end

See: free face.

free face

a. A longwall face with no props between the conveyor and the coal. See also: prop-free front.

b. A surface in the vicinity of a shothole at which the rock is free to move under the force of the explosion. c. The exposed surface of a mass of rock, or of coal. Also called free end.

free fall

a. An arrangement by which, in deep boring, the bit is allowed to fall freely to the bottom at each drop or downstroke.

b. The process of operating the drill. Often called Russian, Canadian, or Galician free fall.

free falling

In ball milling, the peripheral speed at which part of the crop load breaks clear on the ascending side, and falls clear to the toe of the charge.

free-falling device

A sliding piece in percussive boring designed to reduce the vibration and jarring effects when the downward movement of the chisel is suddenly arrested by striking the bottom of the borehole. The lower portion (which is attached to the chisel) is free to slide up and down in a slot provided in the upper part of the joint. When the chisel strikes the bottom of the hole, the slot allows the rods to continue the downward movement without being jarred by the blow of the chisel. See also: jar.

free fed

In comminution, rolls are said to be free fed when fed only enough material to keep a ribbon of ore between the rolls. This results in a remarkably uniform product. CF: choke fed.

free ferrite

Ferrite in steel or cast iron other than that associated with cementite in pearlite.

free field stress

The stresses existing in rock before the excavation of any mine opening. In general, these stresses are known to be influenced primarily by the weight of the overlying material, the relation of the opening of the rock masses around it (depth of overburden, etc.), the physical characteristics to the surrounding rock, and tectonic forces.

free gold

a. Gold uncombined with other substances.

b. Placer gold.

free haul

The distance every cubic yard is entitled to be moved without an additional charge for haul.


Applied to ores that contain free gold or silver, and can be reduced by crushing and amalgamation without roasting or other chemical treatment.

free-milling gold

Gold with so clean a surface that it readily cyanides after liberation by comminution.

free-milling ore

Ore containing gold that can be readily cyanided.

free moisture

a. Moisture in coal that can be removed by ordinary air drying. CF: combined moisture.

b. The part of the total moisture that is lost by a coal in attaining approximate equilibrium with the atmosphere to which it is exposed. c. Moisture not retained or absorbed by aggregate. d. See: moisture content. e. Moisture removable by air-drying under standard conditions. Also called surface moisture. f. See: free water.

free on board

a. Price of consignment to a customer when delivered, with all prior charges paid, onto a ship or truck.

b. Free on rail (f.o.r.) describes similar delivery to rail.

free particles

Particles of ore consisting of a single mineral.

free-piston drive sampler

A drive-sample barrel in which a piston is free to move upward with the top of the sample during the actual dry-sampling operation.

free radical

a. A chemical species that is uncharged and has one or more unpaired electrons.

b. An atom or molecule with at least one unpaired electron.

free settling

As opposed to hindered settling in classification, free fall of particles through fluid media.

free share

Som. A certain proportion of a royalty on coal, paid to lessor by lessee.

free silica

Quartz occurring in granites.

free split

In parallel ventilation flow, the branch or airway that does not require artificial resistance (a regulator) to achieve its design air quantity. See also: open split.


Any stone (esp. a thick-bedded, even-textured, fine-grained sandstone) that breaks freely and can be cut and dressed with equal ease in any direction without splitting or tending to split. The ease with which it can be shaped into blocks makes it a good building stone. The term was originally applied to limestone, and is still used for such rock. CF: flagstone.

free streaming

A combustible gases roof layer flowing under the action of buoyancy without ventilation.

free wall

The wall of a vein filling that scales off cleanly from the gouge.

free water

a. Water that is free to move through a soil mass under the influence of gravity. Also called ground water; phreatic water.

b. Water in soil in excess of hygroscopic and capillary water; also called gravity water. c. The quantity of water removed in drying a solid to its equilibrium water content.

free-water elevation

See: water table.

free-water level

The surface of a body of water in contact with the atmosphere; i.e., at atmospheric pressure.

free-water surface

See: water table.

free way

A direction of easy splitting in a rock.


a. To permit drilling tools, casing, drivepipe, or drill rods to become lodged in a borehole by reason of caving walls, or impaction of sand, mud, or drill cuttings, to the extent that they cannot be pulled out. Also called bind; seize.

b. The act or process of drilling a borehole utilizing a drill fluid chilled to -30 degrees C to -40 degrees C, as a means of consolidating, by freezing, the borehole wall materials and/or core as the drill bit penetrates a water-saturated formation, such as sand, gravel, etc.


a. Used in much the same sense as definition a. of "freeze."

b. Applicable when drill rods become fastened by solidification or freezing of the drilling fluid in a borehole drilled in permafrost. c. To become or be fixed in ice.

freeze proofing

A surface treatment, as with calcium chloride solution, to prevent or reduce cohesion of coal particles by ice formation during freezing weather.

freeze sinking

Use of circulating brine in a system of pipes to freeze waterlogged strata so that shafts can be sunk through them, established, and lined.

freeze-thaw action

See: frost action.


In ball milling, the theoretical rate of revolution at which the contents of the mill are centrifugally held at the circumference.


Consolidation of fine-grained waterlogged soil, enabling excavation to proceed, can be effected by freezing. The process, which dates from 1862, is particularly suitable for shaft sinking.

freezing interval

See: crystallization interval.

freezing method

A method of shaft sinking through loose waterlogged sands that are not suitable for the cementation sinking method. Rings of lined boreholes are put down outside the proposed shaft and in them a very cold solution, such as brine, is circulated until an ice wall has been formed sufficiently thick to enable sinking to proceed normally. The method consists of the following stages: (1) forming a protective wall of ice, with its base in an impervious deposit; (2) maintaining the ice wall until the sinking and lining of the shaft has been completed, and (3) thawing out the ground without damage to the shaft. The freezing method has been revived, largely due to the successful use of bulk concrete, backed by corrugated sheets in place of tubbing, for lining the shaft through the frozen ground. This is followed by wall grouting. Freezing was introduced originally in 1883 by F. H. Poetsch. See also: Oetling freezing method; chemical soil consolidation; silicatization process.


An isometric mineral, (Ag,Cu,Fe) (sub 12) (Sb,As) (sub 4) S (sub 13) ; tetrahedrite group; forms series with argentotennantite and with tetrahedrite; occurs as tetrahedra; in Idaho, Colorado, Nevada, and Germany.


A monoclinic mineral, AgPbSbS (sub 3) . Occurs with pyrargyrite, argentite, and galena in late-stage silver ores at Hiendelaencina, Spain; Freiberg, Germany; Oruro, Bolivia; and Rosebery, Tasmania, Australia.

Fremont etching reagent

An etchant consisting of 10 g of iodine and 20 g of potassium iodide in 100 mL of water.

French chalk

A soft, white variety of talc, steatite, or soapstone finely ground into powder.

French drain

A covered ditch containing a layer of fitted or loose stone or other pervious material.

French process

A process in which zinc is distilled and the vapor burned to produce the oxide; the purity of the oxide is controlled by the purity of the metal.

Frenier sand pump

Spiral ribbon of steel enclosed between two steel disks, mounted on a horizontal hollow shaft into which pulp picked up peripherally is discharged during slow rotation.

Frenkel defect

A type of "point defect" in a crystal structure where an atom or ion is displaced from its normal position to an interstitial one. CF: crystal defect; point defect; interstitial; Schottky defect.


S. Staff. Said of coal crushed by the creep or subsidence of the cover.

frequency factor

In crystallography, the number of different families of planes having the same form.

frequency rate

The rate of occurrence of accidents as determined by multiplying the actual number of injuries in any given period by 200,000 and dividing the product by the number of man-hours exposure. Syn: incidence rate.

frequency response

a. The percentage response of a seismic amplifier for various frequencies at a given filter setting.

b. Attenuation as a function of frequency produced by passage of a signal through an element, such as a geophone or filter.


Said of a rock or rock surface that has not been subjected to or altered by surface weathering, such as a rock newly exposed by fracturing. Syn: unweathered.

fresh air

Air free from the presence of deleterious gases. Pure air.

fresh-air base

An underground station, located in the intake airway, that is used by rescue teams during underground fires and rescue operations. The base should be as close to the fire as safety will permit, adequately ventilated, and in constant touch with the surface by telephone.


a. A great rise in, or a sudden overflowing of, a small stream, usually caused by heavy rains or rapidly melting snow in the highlands at the head of the stream; a rapidly rising flood, usually of minor severity and short duration. See also: flash flood.

b. A small clear freshwater stream or current flowing swiftly into the sea; an area of comparatively fresh water at or near the mouth of a stream flowing into the sea. c. A small stream flowing swiftly into a lake (as in the spring) and often carrying a heavy silt load during its peak flow.

fresh water

a. Water containing less than 1,000 mg/L of dissolved solids; generally, water with more than 500 mg/L is undesirable for drinking and for many industrial uses (Solley et al., 1983).

b. In general usage, the water of streams and lakes unaffected by salt water or salt-bearing rocks. Syn: sweet water. Also spelled freshwater; fresh-water.

fresh-water limestone

A limestone formed by accumulation or precipitation in a freshwater lake, a stream, or a cave. It is often algal and sometimes nodular. See also: underclay limestone.


A tetragonal mineral, Ba (sub 2) TiSi (sub 2) O (sub 8) ; yellow with yellow fluorescence; resembles idocrase.


A result of honeycomb weathering, consisting of small pits in a rock surface that become fewer as they grow larger and deeper.


A monoclinic mineral, Na (sub 2) (Ti,Fe) (sub 8) O (sub 16) ; forms pseudohexagonal crystals in an apatite-rich alkali pegmatite at Katzenbuckel, Odenwald, Germany.

Freudenberg plates

Iron plates suspended in dust chambers for the purpose of settling dust and condensing fumes that escape from the furnace with the gases.


A rare-earth-rich variety of thorite from Brevik, Norway.


Tendency for particles to break down in size (degrade) during storage and handling under the influence of light physical forces.


a. Said of a rock or mineral that crumbles naturally or is easily broken, pulverized, or reduced to powder, such as a soft or poorly cemented sandstone.

b. Said of a soil consistency in which moist soil material crushes easily under gentle to moderate pressure (between thumb and forefinger) and coheres when pressed together.

friable amber

See: gedanite.

friable formation

A rock that breaks easily or crumbles naturally; hence a formation from which good core cannot be obtained easily.


Mechanical resistance to the relative motion of contiguous bodies or of a body and a medium.

frictional electricity

Electrostatic charge developed by rubbing amber, tourmaline, topaz, diamond, and some plastic imitations with a cloth.

frictional force

The force required to overcome friction when a set of tubs or a run of wagons is hauled along a level track at uniform speed. For ordinary pit tubs the frictional force is about 40 lb/st (20 kg/t) load, and for mine cars or wagons it is about 28 lb/st (14 kg/t) load. This resistance is sometimes called traction.

frictional grip

Adhesion between the wheels of a mine locomotive and the rails of the track, its magnitude depending only on locomotive weight and the coefficient of friction between the wheels and track.

friction breccia

A breccia composed of broken or crushed rock fragments resulting from friction; e.g., a fault breccia.

friction factor

A factor that measures an airway's drag on the air moving through it. The friction factor for an airway is found by determining the drop in total pressure over a measured length.

friction head

a. That part of the hydraulic-feed yoke on a diamond drill containing the bearings by means of which the thrust of the hydraulic-feed pistons is transmitted to the drive rod in the drill swivel head. Syn: cage; collar.

b. The additional pressure that the pump must develop to overcome the frictional resistance offered by the pipe, by bends or turns in the pipeline, by changes in the pipe diameter, by valves, and by couplings. c. The pressure required to overcome the friction created by the flow of a confined liquid, such as the flow of a drill fluid through drill rods.

friction loss

See: friction head.

friction socket

A tubular-shaped or slightly inside-tapered fishing tool. The inside surface of the tool is nearly covered with circular pinged protuberances, which, when driven over the lost drill tools, wedge the tools in the socket.

friction yielding prop

See: mechanical yielding prop.


A monoclinic mineral, 6[(Mn,Fe) (sub 8) Si (sub 6) O (sub 15) (OH,Cl) (sub 10) ] ; pseudotrigonal; in manganese skarns, with other manganese silicates; a source of manganese in Sussex County, NJ.


An orthorhombic mineral, Ag (sub 2) Fe (sub 5) S (sub 8) ; in cobalt-nickel-silver ores in Saxony, Germany, and Joachimsthal (Jachymov), Czech Republic.

fringe water

Water of the capillary fringe.

fringing reef

An organic reef that is directly attached to or borders the shore of an island or continent, having a rough, tablelike surface that is exposed at low tide; it may be more than 1 km wide, and its seaward edge slopes sharply down to the sea floor. There may be a shallow channel or lagoon between the reef and the adjacent mainland. Syn: shore reef.

Frisbie's feeder

A device whereby a bucket of coal is forced up into the eye of a pot furnace from below.


See: firth.


The partial melting of grains of quartz and other minerals, so that each grain becomes surrounded by a zone of glass. Fritting results from the contact action of basalt and related lavas on other rocks (Johannsen, 1931).


a. The point of intersection of the inner rails, where a train or tram crosses from one set of rails to another. The frog is in the form of a V. See also: turnout.

b. A combination of rails so arranged that the broad tread of the wheel will always have a surface on which to roll and the flange of the wheel will have a channel through which to pass. See also: rerailer.

frog size

A track haulage term for any distance from the point of the frog to the spread divided by the width of the spread at the place where the measurement was taken.


An orthorhombic mineral, FeTe (sub 2) ; marcasite group; forms a series with mattagamaite; sp gr, 8.07; associated with gold, altaite, petzite, and other gold and tellurium minerals in polished ore at Montbray, PQ, Canada.


A triclinic mineral, CaB (sub 2) (OH) (sub 8) ; occurs with calciborite in limestone skarn from Novo-Frolov copper mine, Turinsk district, northern Urals, Russia.

Froment process

A flotation process in which a sulfide ore is agitated in water with a little oil and sulfuric acid; the sulfide particles become oiled and attach themselves to, and are floated by, gas bubbles.


An orthorhombic mineral, MnFe (sub 4) (PO (sub 4) ) (sub 3) (OH) (sub 5) ; forms a series with rockbridgeite; an alteration mineral in granite pegmatites in the Black Hills of South Dakota, New Hampshire, and Minas Gerais, Brazil.


a. A designation for the mouth or collar of a borehole. See also: face.

b. A metamorphic zone of changing mineralization developed outward from an igneous mass. CF: basic front. c. The working attachment of a shovel, such as a dragline, hoe, or dipper stick. d. In connection with concepts of granitization, the limit to which diffusing ions of a given type are carried; e.g., the simatic front is the limit to which diffusing ions carried the calcium, iron, and magnesium that they removed from the rocks in their paths. The granitic front is the limit to which diffusing ions deposited granitic elements.

front abutment pressure

The release of energy in the superincumbent strata above the seam, induced by the extraction of the seam.

front-end equipment

The attachments to a crane that enable it to work as an excavator, a skimmer, a back acter, or a similar machine. See also: jib.

front-end loader

a. A tractor loader with a digging bucket mounted and operated at the front end of the tractor.

b. A tractor loader that both digs and dumps in front. See also: tractor shovel.


See: foreland.


A monoclinic mineral, PdBi (sub 2) ; forms minute metallic grains in mill concentrates at the Frood Mine, Sudbury, ON, Canada.

frost action

a. The mechanical weathering process caused by repeated cycles of freezing and thawing of water in pores, cracks, and other openings, usually at the surface.

b. The resulting effects of frost action on materials and structures. Syn: freeze-thaw action; frost splitting.

frost-active soil

A fine-grained soil that undergoes changes in volume and bearing capacity due to frost action (Nelson & Nelson, 1967).

frost boil

a. A local accumulation of excess water and mud liberated from ground ice by accelerated spring thawing, softening the soil and causing a quagmire.

b. A break in a surface pavement due to swelling frost action; as the ice melts, soupy subgrade materials issue from the break.

frost crack

A nearly vertical fracture developed by thermal contraction in rock or in frozen ground with appreciable ice content. Frost cracks commonly intersect to form polygonal patterns in plan view.

frost creep

Soil creep resulting from frost action.

Frost gravimeter

An astatic gravity meter of the balance type, consisting of a mass at the end of a nearly vertical arm, supported by a main spring inclined to the vertical at about a 45 degrees angle. The beam rises and falls with gravity variation, but is restored to its normal position by a sensitive weighing spring tensioned by a micrometer screw.

frost heaving

The uneven upward movement, and general distortion, of soils, rocks, vegetation, and structures such as pavements, due to subsurface freezing of water and growth of ice masses (esp. ice lenses); any upheaval of ground caused by freezing.


a. A lusterless ground-glass or mat surface on rounded mineral grains, esp. of quartz. It may result from innumerable impacts of other grains during wind action or from deposition of many microscopic crystals; e.g., fine silica secondarily deposited on quartz grains.

b. The process that produces such a surface.

frost line

a. The maximum depth of frozen ground in areas where there is no permafrost; it may be expressed for a given winter, as the average of several winters, or as the greatest depth on record.

b. The bottom limit of permafrost. c. The altitudinal limit below which frost never occurs; applied esp. in tropical regions.

frost mound

A general term for a knoll, hummock, or conical mound in a permafrost region, containing a core of ice; represents a generally seasonal and localized upwarp of the land surface, caused by frost heaving and/or hydrostatic pressure of ground water.

frost pin

A short, heavy iron pin used by surveyors to make a hole in frozen ground so that a wooden peg may be driven without breaking.

frost splitting

The breaking of rock by water freezing in cracks. Syn: frost action; frost weathering; frost wedging.

frost weathering

See: frost splitting.

frost wedging

See: frost splitting.


In the flotation process, a collection of bubbles resulting from agitation, the bubbles being the agency for raising (floating) the particles of ore to the surface of the cell.


A substance used in a flotation process to make air bubbles sufficiently permanent, principally by reducing surface tension. See also: frothing agent.

froth flotation

a. A flotation process in which the minerals floated gather in and on the surface of bubbles of air or gas driven into or generated in the liquid in some convenient manner. See also: film flotation.

b. The separating of finely crushed minerals from one another by causing some to float in a froth and others to remain in suspension in the pulp. Oils and various chemicals are used to activate, make floatable, or depress the minerals. c. A process for cleaning fine coal, copper, lead, zinc, phosphate, kaolin, etc. with the aid of a reagent; the coal or minerals become attached to air bubbles in a liquid medium and float as a froth.

frothing agent

a. A reagent used to control the size and stability of the air bubbles in the flotation process. Syn: foaming agent; frother.

b. A chemical used in the flotation process to aid collector-coated mineral particles to cling to risen air bubbles. The froth thus formed is transient and should persist only long enough to permit its removal from the flotation cell. Terpenes, pine oil, cresyls, amyl alcohol, and alcohol derivatives are among the agents used.

frothing collector

A collector that also produces a stable foam.

froth promoter

A chemical compound used with a frothing agent. Increases greatly the recovery in a flotation process.

frothy amber

See: foamy amber.

Froude's curve

In surveying a curve with offset y, y = x (super 3) / 6 l r, x being the distance from the tangent point, l the length of transition, and r the radius of circular arc.


Said of the contact between the wall of a vein and the mineral deposit filling it, in which the vein material adheres closely to the wall; also, said of the vein material and of the wall.

frozen coal

Coal that adheres strongly to the rock above or below it.

frozen ground

Ground that has a temperature below freezing and generally contains a variable amount of water in the form of ice. CF: permafrost.


A type of spotted slate with spots suggestive of grains of wheat. See also: fleckschiefer; garbenschiefer.

Frue vanner

An ore-beneficiation apparatus consisting essentially of a rubber belt traveling up a slight inclination. The material to be treated is washed by a constant flow of water while the entire belt is shaken from side to side.


The siliceous cell wall of a diatom, consisting of two valves, one overlapping the other. It is ornate, microscopic, and boxlike.


Bright-green chromium muscovite. Syn: chrome mica.


An informal name applied loosely to any indefinite traillike or tunnellike sedimentary structure identified as a trace fossil but not referred to a described genus. It was once considered to be the remains of the marine alga Fucus, and later was regarded as a feeding burrow of a marine animal and assigned to the plantlike genus Fucoides. The term has been broadly applied to crustacean tracks, worm burrows, molluscan trails, marks made by the tide or waves, and rill marks.


Bitumen derived from the hydration of fucose pentosane and found among clays and sands in California.


A substance that can be economically burned to produce heat energy for domestic or industrial purposes. Fuels include compounds of carbon and hydrogen and exclude other substances that can be burned. Fuels can be subdivided into recent plant fuels, fossil fuels, such as peat and coal, and products of distillation of plant or fossil fuels. According to their state of aggregation, fuels can be subdivided into solid, liquid, and gaseous fuels.

fuel feeder

A contrivance for supplying a furnace with fuel in graduated quantities. A mechanical stoker.

fuel ratio

The ratio of fixed carbon to volatile matter in coal.

fugitive air

Applied to air moving through the fan that never reaches the working faces. It leaks through poor stoppings, around doors and so on, back into the returns without moving anywhere near the active sections. Surveys of some mines show that up to 80% of the air moving through the fan never reaches the working faces.

fugitive constituent

A substance that was present in a magma but was lost during crystallization, so that it does not commonly appear as a rock constituent.

fugitive dust

The particulate matter not emitted from a duct or stack that becomes airborne due to the forces of wind or surface coal mining and reclamation operations or both. During surface coal mining and reclamation operations it may include emissions from haul roads; wind erosion of exposed surfaces, storage piles, and spoil piles; reclamation operations; and other activities in which material is either removed, stored, transported, or redistributed.


A pivot for a lever.


A sudden glistening of molten gold or silver at the close of cupellation.


An irregular, glassy, often tubular or rodlike structure or crust produced by the fusion of loose sand (or rarely, compact rock) by lightning, and found esp. on exposed mountain tops or in dune areas of deserts or lake shores. It may measure 40 cm in length and 5 to 6 cm in diameter. Etymol. Latin fulgur, lightning. Syn: lightning tube.

full dip

See: true dip; dip.

fuller's earth

A clay or claylike material with a high adsorptive capacity, consisting largely of the clay minerals montmorillonite and palygorskite. Used originally in England for whitening, degreasing, or fulling (shrinking and thickening by application of moisture) woolen fabrics; fuller's earth now is extensively used as an adsorbent in refining and decolorizing oils and fats; it is a natural bleaching agent. Its color ranges from light brown through yellow and white to light and dark green; it differs from ordinary clay by having a higher percentage of water and little or no plasticity, tending to break down into a muddy sediment in water. Fuller's earth probably forms as a residual deposit by decomposition of rock in place, as by devitrification of volcanic glass. The term is applied without reference to any particular chemical or mineral composition, texture, or origin. Syn: walker's earth.

full-face blast

The standard type of heading blast consists of a straight in or main drive, at right angles to the rock face, and a back drive at right angles to the main drive and parallel to the face. The main drive is normally driven at quarry floor level to a depth of 0.6 times the height of rock above the back drive. Apart from exceptional circumstances, the maximum depth of the main drive should be 50 ft (15 m), so that with faces over 85 ft (26 m) high the 0.6 ratio should not be used, but the main drive limited to 50 ft.

full-face firing

With modern drilling equipment, it is now possible, in suitable conditions, to drill small-diameter holes from top to bottom of the face, and where this can be done considerable advantages as to cost and efficiency can be obtained as compared with the bench method. In high faces of 50 ft (15 m) and upward it is not always easy to drill vertical holes to give small burdens because of the breakback of the rock at the crest of the quarry face. It is therefore recommended that larger burdens be taken and that the vertical holes be supplemented by breast holes at quarry floor level. These holes are intended to permit concentrated explosive charges to blow out the toe rock, while the explosive in the vertical holes brings down the rock from the face.

full gage

a. A cylindrical or tubular object, such as a bit or reaming shell, the outside and/or inside diameters of which are the size specified. Also called full size.

b. A borehole the inside diameter of which is uniform enough to allow a new-condition bit to follow portions of the hole drilled by other bits cutting the same X-borehole size without reaming. c. As applied to deflection drilling, the branch borehole is the same diameter as the parent hole.

full-seam mining

A mining system, brought on by the advent of mechanical loading and mechanical coal cleaning, in which the entire section is dislodged together and the coal separated from the rock outside of the mine by the cleaning plant.

full subsidence

The greatest amount of subsidence that can occur as a result of mine workings. See also: percentage subsidence.

full teeter

A condition of teeter in which the maximum degree of fluidization of the suspension is attained but without disruption of the bed.

full velocity

See: settling velocity.

full-wave rectifier

A rectifier that changes single-phase alternating current into pulsating unidirectional current, utilizing both halves of each cycle.

fully developed mine

In coal mining, a mine in which all development work has reached the boundaries and further extraction will be done on the retreat.


An explosive compound of mercury, HgC (sub 2) N (sub 2) O (sub 2) , that is employed for the caps or exploders, by means of which charges of gunpowder, dynamite, etc., are fired.


A monoclinic mineral, Pb (sub 3) Sb (sub 8) S (sub 15) ; soft metallic gray; occurs with zinkenite and sphalerite in Romania and Hungary.


An old syn. for brown coal.


a. A hole or a vent from which fumes or vapors issue; a spring or a geyser that emits steam or gaseous vapor. Usually found in volcanic areas.

b. The exhalation from a fumarole consists of water vapor, nitrogen, hydrogen, free hydrochloric acid, hydrofluoric acid, and silicon fluoride. CF: solfatara; mofette; soffioni. c. A hole in a volcanic region, from which gases and vapors issue at high temperature.


a. The gas and smoke, esp. the noxious or poisonous gases, given off by the explosion or detonation of blasting powder or dynamite.

b. Consists of very fine particles of metals or metallic compounds that have been volatilized at the high temperatures of furnaces, condensed at lower temperatures, and carried by furnace gases into the flues. In general, all the volatile constituents of the ore charge are represented. See also: metallurgical fume.

fume quality

A measure of the toxic fumes to be expected when a specific explosive is properly detonated.

fundamental complex

See: basement complex.

fundamental jelly

Structureless colloidal jelly that forms the base of coals and is assumed to have been produced by the decay of plant materials. See also: carbohumin.

fundamental strength

The maximum stress that a substance can withstand, regardless of time, under given physical conditions, without creep.

fundamental substance

See: fundamental jelly; carbohumin.

fungus subterraneus

An old name for elaterite.

funicular railway

A railway that negotiates a steep gradient; the cars are operated by cables and winches. See also: mountain railway.

funnel box

A square funnel forming one of a series of gradually increasing size; for separating metal-bearing slimes according to fineness. See also: spitzkasten.

funnel brick

Funnel-shaped fireclay piece used in the bottom-pour ingot assembly to lead metal to the fountain brick. See also: bottom-pour ingot assembly.

funnel intrusion

See: lopolith.

funnel joint

A joint in a joint set that is concentric, with the joints dipping toward a common center.


Coolies working tin mines or other projects, in Malaysia.


Eng. A deposit of chemical salts and other material (sediment) upon the inner sides of pumps, boilers, etc. Also called: furring.


A round rod used for sounding a bloomery fire. Syn: tempering bar.


a. A structure in which, with the aid of heat so produced, (1) the operations of roasting, reduction, fusion, steam-generation, desiccation, etc., are carried on, or, (2) as in some mines, the upcast air current is heated, to facilitate its ascent and thus aid ventilation.

b. Structure in which materials are exposed to high temperatures. Fuels used to maintain this include alcohols, paraffins, gas, coal, hydrogen, electricity, wood, and sulfur. A furnace is called batch type if its contents are treated in successive charges, or continuous when a stream of material passes through, being changed during transit. The main types are (1) the arc, which uses the heat of an electric arc; (2) the blast furnace; (3) the crucible furnace, a laboratory appliance for heating small charges, or, if large, for melting metals held in bigger crucibles; (4) the induction furnace, heated by electrically induced currents; (5) the muffle, in which the material is placed in a sleeve not in direct contact with the heating atmosphere, so that close control of entering and departing gas is possible; (6) the reverberatory, in which head developed on the roof is reflected onto a horizontal bed below; (7) the revolving furnace, a horizontal cylinder; (8) the roasting furnace in which material is oxidized, kilned to drive off carbon dioxide, or heated to remove moisture. See also: cupola; continuous furnace; converter.

furnace bridge

A barrier of firebricks or an iron-plate chamber filled with water thrown across the furnace at the extreme end of the fire bars to prevent fuel from being carried into the flues and to quicken the draft by contracting the section of the current of hot gas.

furnace cadmium

The zinc-cadmium oxide that accumulates in the chimneys of furnaces smelting zinciferous ores. See also: cadmia.

furnace charger

a. A weighing apparatus for feeding into a furnace mouth the proper proportions of ore, fuel, etc.

b. In the iron and steel industry, a laborer who operates a compressed-air-driven arm to push stock steel rails into a heating furnace. See also: charging person.

furnace conveyor

The conveyor that moves material through a furnace.

furnace holding-the-iron

A condition by which the furnace gives much less than the normal amount of iron at casting although the feeding may have been regular. The taphole runs iron slowly, and the amount of cinder is somewhat scanty. CF: furnace losing-the-iron.

furnace linings

Refractory materials used to protect the walls of the furnace from reaction with its molten contents (abrasive, melting, or chemical). Three divisions are (1) acid refractories rich in silica (flint, ganister, fireclay), which react with basic oxides; (2) neutral refractories (chromite, graphite), and (3) basic refractories, rich in oxides of calcium and magnesium and low in silica.

furnace losing-the-iron

Escape of iron from the hearth of a blast furnace into the foundation beneath, indicated by decreased quantity of iron at casting and appearance of slag at the tapping hole. Syn: losing iron.

furnace magnesite

A mortar material prepared from finely ground, dead-burned magnesite; suitable for use as a joint material in laying magnesite brick, and for patching or daubing furnace masonry.

furnace sprayer

In ore dressing, smelting, and refining, a laborer who sprays the inner surfaces of furnace walls and roof with a slurry of silica, water, and fireclay to protect brick, using a compressed-air gun. Also called slurry man; sprayer.

furnace stack

A chimney built over a furnace for increasing the draft.


Misspelling of fornacite. See: fornacite.


See: foreigner.


Having deep grooves or striations.


a. A coal lithotype characterized macroscopically by its silky luster, fibrous structure, friability, and black color. It occurs in strands or patches and is soft and dirty where not mineralized. Its characteristic microlithotype is fusite. CF: vitrain; clarain; durain. Syn: mineral charcoal; mother of coal. Obsolete syn. motherham.

b. Coal material having the appearance and structure of charcoal. It is friable, sooty, generally high in ash content, and consists mainly of fusite.


An igniting or explosive device in the form of a cord, consisting of a flexible fabric tube and a core of low explosive (safety fuse) or high explosive (detonating cord).

fuse auger

An instrument for regulating the time of burning of a fuse by removing a certain portion of the composition. It has a movable graduated scale that regulates the depth to which the auger should penetrate.

fuse cutter

A mechanical device for cutting safety fuse clean and at right angles to its long axis.

fused alumina

Aluminum oxide, Al (sub 2) O (sub 3) .

fused bath electrolysis

Extraction of metals by electrolytic decomposition of their fused salts; extraction of metals from electrolytically decomposable compounds dissolved in substances inert under the conditions of electrolysis.

fuse detonator

A detonator which is initiated by a safety fuse; also referred to as an ordinary blasting cap.

fused nip

A terminal connection, with a fuse, used on portable electrical mining machinery.

fused quartz

Silica glass made from clear pieces of vein quartz.

fused refractories

Refractories in which the constituents are held together by heating to either the point of fusion or coalescence.

fused trolley tap

A specially designed holder with enclosed fuse for connecting a conductor of a portable cable to the trolley system or other circuit supplying electric power to equipment in mines.

fuse gage

An instrument for cutting time fuses to length.


That part of an electric detonator consisting of twin metal conductors, bridged by fine resistance wire, and surrounded by a bead of igniting compound that burns when the firing current is passed through the bridge wire.

fuse lighter

Pyrotechnic devices such as a hot-wire fuse lighter or igniter cords for the rapid and certain lighting of safety fuse. See: tchesa stick.

fuse lock

A friction lock by which a miner may fire the free end of a blasting fuse by a lanyard.

fusibility scale

A temperature scale based on the fusibility of a standard group of minerals. Used prior to the development of modern furnaces.

fusible plug

An insert of metal with low melting point placed in boilers, sprinklers, and other devices to melt when the temperature becomes dangerously high, so that the melting will relieve pressure, allow water flow, or otherwise tend to alleviate the dangerous condition.

fusing point

The degree of heat at which any substance begins to melt or liquefy. See also: melting point.


a. A maceral of coal within the inertinite group with intact or broken cellular structure, a reflectance (except in meta-anthracite) well above that of associated vitrinite, and a particle size generally greater than about 50 mu m except when isolated from other macerals. CF: fusain.

b. A constituent showing well-defined cellular structure of wood or sclerenchyma. The cell cavities vary in size and shape--round, oval, or elongated. Bogen structure is common. Occurs as discrete lenses, thin partings or bands, and as small dispersed fragments; is widely distributed; common. The physical and chemical properties of fusinite vary only slightly in coals of different rank, and consequently its technological properties are fairly constant. c. The major maceral, or micropetrologic, constituent of fusain. It consists of wood (xylem or lignified tissue) of which very little is left but woody tracheids or thick-walled elements so highly carbonized as to contain only traces of ulmins. A member of the inertite group.


A process of coalification in which fusain is formed. CF: incorporation; vitrinization. Also spelled: fusainisation.


Fusain and similar material in coal.


a. A union by or as if by a combination of ingredients achieved by heating, and mixing together.

b. The union of atomic nuclei to form heavier nuclei, resulting in the release of enormous quantities of energy when certain light elements unite. Also called nuclear fusion. CF: fission.

fusion button test

See: button test.

fusion method

A method used to remove certain impurities from diamond concentrate with a particle size of 0.5 to 1.0 mm. The material, mixed with 10 times its weight of flake caustic soda, is placed in crucibles and put in a furnace where a temperature of 650 degrees C is maintained for 45 min. After furnacing, the material is rinsed to remove the caustic soda and boiled in a glass beaker containing a solution of 1 part hydrochloric acid and 4 parts water. After further rinsing, the diamond, free from satellites, is dried on a hotplate.

fusion of clay

The stage on heating a clay wh�,�he material is changed from the solid to the liquid state, but complete liquefaction occurs so gradually with most clays that a fusion range and not a fusion point is obtained. See also: squotting.

fusion-piercing drill

A machine designed to use the fusion-piercing mode of producing holes in rock. Sometimes incorrectly called a jet drill. Syn: jet-piercing drill.

fusion point

The temperature at which melting takes place. Most refractory materials have no definite melting points, but soften gradually over a range of temperatures.

fusion tectonite

Igneous rock consolidated from a flowing magma.

fusion test

See: pyrometric cone equivalent; button test.


a. A coal microlithotype that contains at least 95% fusinite. It is a variety of inertite. CF: fusain.

b. In 1955 the Nomenclature Subcommittee of the International Committee for Coal Petrology resolved to use this term for the microlithotype consisting principally of the macerals fusinite, semifusinite, and sclerotinite. Two varieties of fusite are distinguishable--a fragile and powdery fusite and a hard consolidated fusite in which the cavities are filled by various minerals, carbonates, sulfides, kaolin, and other clay minerals. Widely distributed, but in general not abundant. Occurs in fine bands and lenses of varying thickness. The soft variety of fusite concentrates in the very fine particle sizes. Hard fusite distributes itself in various sizes (depending on the thickness of the original bands or lenticles in the seam), but not in the fines. This form of fusite is usually discarded in the middlings and refuse. c. A coal microlithotype containing 95% or more fusinite, plus semifusinite, plus sclerotinite.


A type coal rock consisting of the macerals fusinite and vitrinite; it may contain all other macerals. Fusinite is present in a smaller quantity than in clarofusain. CF: clarofusain.


a. Durain in which much of the microconglomeratic elements consist of fusain.

b. Judged obsolete by the Heerlen Congress of 1935.


a. Preferred. Coal consisting of material transitional between fusain and vitrain with vitrain being predominant (Heerlen Congress of 1935). CF: vitrofusain.

b. Coal consisting of a mixture of vitrain with fusain fragments.


See: fusulinid.


Any foraminifer belonging to the suborder Fusulinina, family Fusulinidae, characterized by a multichambered elongate calcareous microgranular test, commonly resembling the shape of a grain of wheat. Range, Ordovician to Triassic. Syn: fusuline.

future ore

See: possible ore.