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

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a. A concentration of a substance that is detectable, but too minute for accurate quantitative determination.

b. A quantity of precipitation that is insufficient to be measured by a gauge. c. A sign, evidence, or indication of a former presence; specif. a mark left behind by an extinct animal, such as a trace fossil. d. The record of the output of one geophone group with time after the shot, displayed on paper, film, or magnetic tape. e. The intersection of a geological surface with another surface, e.g., the trace of bedding on a fault surface, or the trace of a fault or outcrop on the ground. CF: trend; strike. f. A very small quantity of a chemical constituent or component, esp. when not quantitatively determined because of extremely low concentrations. g. To follow the lode on the surface, and to lay it open by long pits. h. Recording on the seismogram of a single seismometer station.

trace-by-trace plotting

A procedure used in seismic reflection where reflection times from all traces, or sometimes alternate traces, are plotted at the reflecting point positions (midway between shot and detector). When no correction has been made for "normal moveout," the plotted times appear to lie along arcs that are convex upward and straddle the shot positions symmetrically. CF: center-trace time.

trace element

a. An element that is not essential in a mineral, but that is found in small quantities in its structure or adsorbed on its surfaces. Although not quantitatively defined, it is conventionally assumed to constitute significantly less than 1.0% of the mineral. Syn: accessory element; guest element.

b. An element that occurs in minute quantities in plant or animal tissue and that is essential physiologically. Syn: minor element; microelement.


An element or compound that has been made radioactive so that it can be followed (traced) easily in industrial and biological processes. Radiation emitted by the tracer (radioisotope) pinpoints its location. Abbrev., tcr.

tracer gas

A gas introduced in small quantities into the main body of air to determine either the air current or the leakage paths in a ventilation system.

tracer-gas technique

This method, as applied for the measurement of airflow in headings, can be used for determining velocities below the working range of the vane anemometer. The tracer used is normally nitrous oxide. The technique consists of releasing a quantity of tracer gas, either instantaneously or over a timed interval. The tracer then diffuses throughout the airstream until a position is reached where it is uniformly dispersed over the cross section of the airway. At such a position, samples are taken and these are put through the analyzer to determine the gas concentration.

tracer test

In ground water hydrology, a field technique for estimating transport parameters by injecting a tracer (e.g., dye, radioactive substance, or chemical not naturally present in the flow system) and monitoring the time and concentrations at a downgradient location.

trace slip

In a fault, that component of the net slip that is parallel to the trace of an index plane, such as bedding, on the fault plane. See also: trace-slip fault.

trace-slip fault

A fault on which the net slip is trace slip, or slip parallel to the trace of the bedding or other index plane.


An extrusive rock, intermediate in composition between trachyte and andesite, with sodic plagioclase, alkali feldspar, and one or more mafic minerals (biotite, amphibole, or pyroxene). See also: mugearite.


An extrusive rock intermediate in composition between trachyte and basalt, characterized by the presence of both calcic plagioclase and alkali feldspar, along with clinopyroxene, olivine, and possibly minor analcime or leucite. Approx. synonymous with hawaiite.


A group of fine-grained, generally porphyritic, extrusive rocks having alkali feldspar and minor mafic minerals (biotite, hornblende, or pyroxene) as the main components, and possibly a small amount of sodic plagioclase; also, any member of that group; the extrusive equivalent of syenite. Trachyte grades into latite as the alkali feldspar content decreases, and into rhyolite with an increase in quartz. Etymol: Greek trachys, rough, in reference to the fact that rocks of this group are commonly rough to the touch.


a. A textural term applied to volcanic rocks in which feldspar microlites of the groundmass have a subparallel arrangement corresponding to the flow lines of the lava from which they were formed. CF: trachytoid; pilotaxitic.

b. Pertaining to or composed of trachyte.


A textural term originally applied to phaneritic igneous rocks by analogy with the trachytic texture of some lava flows. In such rocks (e.g., many nepheline syenites), the feldspars have a parallel or subparallel disposition; trachytoid is now used for all similar textures, regardless of the composition of the rock in which they occur. CF: trachytic.

tracing float

A process in which float is followed back to its origin. A prospector moves up slope looking for pieces of float until no more are to be seen. If, at this point, no outcrop is visible, the probabilities are that soil or loose surface material covers a hidden outcrop, which can be sought by digging pits or trenches.


a. The groove cut in a rock by a diamond inset in the crown of a bit.

b. A pattern applied to setting diamonds in a bit crown, in which the diamonds are arranged in concentric circular rows so that the diamonds in a specific row follow the track cut by a preceding diamond. c. The slide or rack on which a diamond-drill swivel head can be moved to positions above and/or clear of the collar of a borehole. d. See: conveyor track. e. A crawler track.

track bolt

A chair bolt or coach screw used in fastening rails.

track braking

Track brakes, similar to those used on surface tramcars, may be installed on heavy downgrades underground to supplement other braking systems; they apply blocks to the rails by mechanical, pneumatic, or electromagnetic power. The normal shoe brake must be designed to work in conjunction with the track brakes so that the wheels are not skidded when the track brakes utilize part of the weight of the locomotive. Electromagnetic track brakes may utilize the braking currents produced in rheostatic braking to excite the electromagnets, which are then pulled down onto the rails and produce a strong retarding pull.

track cable

Steel wire rope, usually a locked-coil rope that supports the wheels of the carriers of a cableway.

track cable scraper

This type of excavator operates in general the same as a slackline cableway, except that it uses a bottomless scraper bucket that must convey its load over the ground instead of through the air. Like the slackline cableway, this machine is operated by a two-drum hoist that controls a track cable that spans the working area and a haulage cable that leads to the front of the bucket. Both cables are reeved through sheave blocks attached to a high guyed mast or tower at the head end of the installation. When the bucket comes in with a load and reaches the desired dumping point, a few rotations of the rear drum of the hoist serve to tighten the track cable and lift the bucket off its load; then the brake is released on the front drum that controls the haulage cable, permitting the empty bucket and carrier to glide back down the inclined track cable.

track channeler

In quarrying, a rock channeler designed to operate from a track on which it is mounted; frequently a combined locomotive and channeling machine.

track cleaner

In mining, a laborer who cleans mine track and switches by shoveling coal, ore, rock, mud, and refuse, and throwing it to one side or loading it into a mine car. Also called road cleaner.

track cleaners

A machine to remove gob from railroad tracks, between rails, and to a distance of 48 in (1.2 m) from the track centers. Digger plates remove gob to the top of ties, while wings on either side of the machine gather it from the sides of the track into the track, to be moved by conveyors to a car at the machine's rear. One person operates the towing motor and observes the digging, while another controls the digging plate height, adjusts wing plows, and observes loading.

track diamonds

Diamonds set in the face or lead portion of the drill-bit crown. Syn: track stones.

track frame

In a crawler mounting, a side frame to which the track roller and idler are attached. Also called truck frame.

track gage

a. The distance between the inside edges of installed railway rails.

b. The minimum track gage that should be used on a modern haulage system is 3 ft 6 in (1.07 m). This gage has been established as a standard by the American Mining Congress as a result of the consensus of opinion of mining engineers and manufacturers in the United States. c. See also: rail gage.

track haulage

Movement or transportation of excavated or mined materials in cars or trucks running on rails.

tracklaying tractor

A tractor moving on crawler tracks.

trackless mine

A mine with no rails. In such mines, rubber-tired vehicles operate independently of tracks and are used for haulage and transport.

trackless tunneling

A method of tunneling using loaders mounted on crawler tracks, and a diesel- or battery-powered dump-truck haulage system. See also: rubber-tired haulage.


Referring to the operation of equipment on tracks, such as track-mounted cutting machines, track-mounted loaders, etc.

track-moving machine operator

In metal mining, one who operates a machine that moves and lays track mechanically in open pit mines, picking up a section of track and moving and laying it in the desired position without having to detach rails from ties. Also called track-laying machine operator. Syn: hydraulic jack operator.

track pin

A hinge pin connecting two sections or shoes of a crawler track.

track resistance

The total rolling friction of a train on straight level track. It is generally taken as 30 lb per short ton weight (15 kg/t) of the train for cars having plain bearings and 20 lb/st (10 kg/t) for cars with roller bearings. These figures may be increased by 10 to 15 lb (5.0 to 7.5 kg) if the track is in poor condition and may be less for track in excellent condition.

track roller

In a crawler machine, the small wheels that are under the track frame and that rest on the track. Also called truck rollers.

track shifter

A machine or appliance used in shifting a railway track laterally. Also the operator of such a device or machine. See also: shifter.

track spike

A heavy steel nail of square section that is driven into a wooden sleeper to hold a flanged rail.

track stones

See: track diamonds.

track wheel

One of a set of small flanged steel wheels resting on a crawler track and supporting a track frame.


a. The act of drawing a vehicle over a surface and the force exerted in so doing. Traction is the friction developed between tracks or tires and the surface of the ground on which they are moving.

b. The total amount of driving push of a vehicle on a given surface.

tractive efficiency

A measure of the proportion of the weight resting on tracks or drive wheels that can be converted into vehicle movement.

tractive effort

a. The effort exerted by a locomotive at the rim of its driving wheels; it is a function of its weight, the nature of its tires, and the condition of the track. It is equal to the weight of the locomotive times the adhesion of the locomotive to the track. For steel wheels on clean dry track the adhesion is 25%, and the tractive effort is therefore 500 lb/st of weight (250 kg/t). For cast-iron wheels the adhesion is 20%.

b. The necessary drawbar pull plus the resistance of the locomotive itself. c. See: tractive force.

tractive force

a. The pull exerted by a haulage rope on the drawbar of a car to overcome the frictional resistance of the car and the force of gravity acting on it. Also, the force available at the wheels of a locomotive to move the machine and its attached load. Syn: tractive effort.

b. The pull that a locomotive is capable of producing at its drawbar. c. In hydraulics, drag or shear developed on the wetted area of a streambed, acting in the direction of flow. As measured per unit of wetted area, unit tractive force equals the specific weight of water times hydraulic radius times slope of channel bed (Chow, 1957).

tractive power

The weight of the vehicle multipled by the coefficient of traction; it is the total pounds of pull that can be exerted before slippage occurs.

tractive resistance

The resistance to motion due to friction per unit weight hauled.


A self-propelled vehicle--which may be mounted on crawler tracks, on wheels with large pneumatic tires, or on a mixture of both--intended for moving itself and other vehicles. See also: wheeled tractor; mine tractor.

tractor drills

These drills have a crawler mounting that supports the feed guide bar on an extendable arm. Small air motors control the movements of the arm used in tilting and turning the guide bar and provide power for crawler movement. The compressor is a separate unit, which can be towed by the tractor drill. Also called a Jumbo.

tractor loader

A tractor equipped with a bucket that can be used to dig, and to elevate to dump at truck height. Also called tractor shovel; shovel dozer.

tractor pan operator

In beneficiation, smelting, and refining, one who scrapes up bauxite ore from stockpiles, hauls the ore to the crusher, and dumps it into the crusher hopper, using a combination bulldozer carryall.

tractor shovel

One of the names applied to a class of excavating equipment that has a bucket supported from the front end of a tractor. See also: loader.

traffic marks

Abrasions that result from metal to metal contact and vibration during transit. These abrasions are usually dark in appearance because of the presence of a dark powder, which consists of aluminum and aluminum oxide fines produced by the abrasive action of surfaces rubbing together.


a. A towed carrier that rests on its own front and rear wheels. Also called full trailer.

b. See: drag.

trailing cable

a. A cable for carrying electricity from a permanent line or trolley wire to a movable machine, such as used in mining or quarrying. The cable is heavily insulated and protected with either galvanized steel wire armoring, extra stout braiding hosepipe, or other material. It is usually paid out from a reel as the machine advances. See also: individually screened trailing cable.

b. A flexible insulated cable used for transmitting power from the main power source, such as a trolley wire, nipping station, or junction box, to a mobile machine. It includes cables between the nipping station and distribution center.

trailing cable coupler

An assembly of two restrained-type sockets for coupling together two trailing cables fitted with restrained plugs.

trail of a fault

Crushed material of a bed or vein that indicates the direction of fault movement; it may be valuable as a guide to the main vein. See also: drag ore.


A number of empty or loaded mine cars, coupled together, for transport by rope haulage or locomotive. See also: journey.

train dispatcher

See: motor boss.

training face

Usually a longwall coal face where new colliery entrants or trainees can gain experience, skills, and confidence in the winning and working of coal.

training gallery

A short tunnel or chamber attached to a rescue station in which rescue workers may receive training in an atmosphere of dense smoke. It is also used to give rescue workers experience in stretcher drill, the use of stretchers, reviving apparatus, tube-breathing apparatus, artificial respiration, etc.

training the belt

Adjusting the troughing idlers, return idlers, or tail or head pulleys forward or back so that conveyor belting will run in the desired position on the conveyor frame to prevent spilling of ore.


The trade name for a mixture of vashegyite with a colloidal zeolitic mineral, used as a gemstone; originates near Manhattan, NV. Originally described as banded variscite. Syn: Sabalite.


In metal mining, a laborer who loads ore into railroad cars.


One mile (1.6 km) traversed by one train; used as a unit in railroad accounting.

train of rolls

A series of mills, one after the other, each successive mill approaching more nearly the size of the finished piece.

train resistance

The grade resistance plus the track resistance.


Line that intersects wave fronts at right angles.


a. A trip of coal cars.

b. Generally, to move a self-propelled piece of equipment other than a locomotive; tramcar. c. A boxlike wagon of steel, running on a tramway or railway in a mine, for conveying coal or ore. Also called tramcar, tub, cocoa pan, corve, corf, or hutch. d. To haul or push trams or cars about in a mine. e. A four-wheeled truck to carry a tub, corve, or hutch.


Eng. A car used in coal mines. Syn: tram.


a. An overfill appearing as two parallel lines on rolled bars.

b. Long, straight marks due to drawn-out inclusions on rolled sheet.


a. A board with two grooves intersecting at right angles, in which the two ends of a beam compass can slide and describe an ellipse.

b. See: beam compass. c. A pivoted rod, used to keep brick in alignment in lining circular kilns.


a. A person who loads broken rock on tramcars and delivers it at the shaft.

b. Trammers work as assistant miners in all the work a miner does. They load the broken mineral onto shaker or belt conveyors, fill and haul the mine cars, bring in the mine timber and other materials to support and equip the mine workings, serve the mining and transport machines, and work also as auxiliary mine timbermen. c. One who transports coal, ore concentrate, or flux to roasting furnaces or bins.


The practice of pushing tubs, mine cars, or trams, by hand. Tramming was an earlier practice in longwall stall mining, but is now largely obsolete. On the surface, tramming means moving material in skips or wagons running on light railway track.

tramming motor

a. An electric locomotive used for hauling loaded trips.

b. The motor in a cutting machine that supplies the power for moving or tramming the machine.

tramp iron

a. Stray metal objects, such as coal-cutter picks or bolts, that have become mixed with the run-of-mine coal or ore.

b. Any loose piece of metal in a borehole.

tramp oversize

Ore that is too large to be handled efficiently by the machine into which it is fed.


Eng. A rail for a tram. A light railroad rail distinguished from tram plate by being rolled while the latter is cast.


A mine haulage road.

tram rope

A hauling rope, to which cars are attached by a clip or chain, either singly or in trips.

tram vibrator

See: vibrating platform.


a. A roadway having plates or rails on which wheeled vehicles may run. Syn: tramroad.

b. A suspended cable system along which material, such as ore or rock, is transported in suspended buckets. See also: aerial tramway. c. A system in which carriers are supported by cable and in which the movement is continuous over one or more spans.

transcurrent fault

A large-scale strike-slip fault in which the fault surface is steeply inclined. Syn: transverse fault; transverse thrust. See also: strike-slip fault.


a. A device actuated by one transmission system and supplying related waves to another transmission system; the input and output energies may be of different forms. Ultrasonic transducers, e.g., accept electrical waves and deliver ultrasonic waves, the reverse also being true.

b. A device that measures physical quantities in a system--such as ground displacement, velocity, or acceleration-- and converts them into related or proportional units of electronic outputs (e.g., voltage, current). CF: geophone.


A vertical or inclined connection between two or more levels; used as an ore pass.

transfer car

a. A quarry car provided with transverse tracks on which the gang car may be conveyed to or from the saw gang.

b. A car equipped with rails, used to transfer a drier or kiln car from one set of tracks to another.

transfer case

A transmission or gearset that provides drive to secondary drives, winches, etc.

transfer chute

A chute used at a transfer point in a conveyor system. The chute is designed with a curved base or some other feature so that the load can be discharged in a centralized stream and in the same direction as the receiving conveyor.

transfer conveyor

Conveyor generally 50 to 300 ft (15 to 90 m) in length. It is used to transport material only from one conveyor to another.

transfer-gang-car system

A system used in quarries to save time in handling stone blocks and slabs. In this system, a transfer car that runs on a depressed track in front of the gangs is provided with a short section of track across the top. A gang car loaded with marble, sandstone, etc., is placed on this track and when moved to proper position is shifted beneath the gangsaw. Similarly, a gang car loaded with sawed slabs may be quickly moved from beneath the saws to the transfer car for transportation to the shops.

transfer gear

Self-actuating mechanism at shaft head by which a skip is emptied and its contents moved away to the next stage of handling.

transfer impedance

a. The transfer impedance of a network made up of a source and a load connected by a transducer is the ratio of the phasor representing the source voltage to the phasor representing the load current of the load.

b. The complex-valued ratio of voltage at one pair of terminals to the current at another pair in a four-terminal network.

transfer point

The point where coal or mineral is transferred from one conveyor to another. See also: loading point.

transfer table

A table connected with rolling mills for laterally transferring work from one mill to the other.


A constitutional change in a solid metal; e.g., the change from gamma to alpha iron, or the formation of pearlite from austenite.

transformation temperature

The temperature at which a change in phase occurs. The term is sometimes used to denote the limiting temperature of a transformation range.

transformed flow net

A flow net whose boundaries have been properly modified (transformed) so that a net consisting of curvilinear squares can be constructed to represent flow conditions in an anisotropic porous medium.


A proponent of the theory that all granites had a metasomatic or palingenic origin. CF: magmatist. Syn: granitizer; antimagmatist.


The entry and exit of any gaseous or hydrothermal fluid in solid rock to produce such rocks as granite. CF: granitization.


See: intracrystalline.


a. The spread or extension of the sea over land areas, and the consequent evidence of such advance (such as strata deposited unconformably on older rocks, esp. where the new marine deposits are spread far and wide over the former land surface). Also, any change (such as rise of sea level or subsidence of land) that brings offshore, typically deep-water environments to areas formerly occupied by nearshore, typically shallow-water conditions, or that shifts the boundary between marine and nonmarine deposition (or between deposition and erosion) outward from the center of a marine basin. Ant: regression. CF: onlap. Syn: invasion; marine transgression.

b. A term used mostly in Europe for discrepancy in the boundary lines of continuous strata; i.e., unconformity. See also: unconformity.

transgressive overlap

See: onlap.

transient velocity

A velocity, different from the steady state velocity, which a primer imparts to a column of powder to start detonation.


A device for controlling or amplifying electric currents by means of potential probes through a crystal of a semiconductor, commonly silicon or germanium.


a. A theodolite in which the telescope can be reversed (turned end for end) in its supports without being lifted from them, by rotating it 180 degrees or more about its horizontal transverse axis.

b. The act of reversing the direction of a telescope (of a transit) by rotation about its horizontal axis.---v. To reverse the direction of a telescope (of a transit) by rotating it 180 degrees about its horizontal axis. Syn: plunge.


A trade name for a material of asbestos fiber and Portland cement molded under high pressure. Used for fireproof walls, roofing, and in lining ovens, etc.

transition belt

A short belt carrying material from a loading point to a main conveyor belt.

transition curve

a. A curve designed to effect a gradual change between a straight and a circular curve.

b. See: spiral curve.

transition elements

a. In the periodic system, those elements characterized by the increment of inner d shells of electrons which may become involved in secondary or hybrid bond formation.

b. Elements having atomic numbers 21 (Sc) to 30 (Zn), 39 (Y) to 48 (Cd), and 57 (La) to 80 (Hg).

transition metals

Elements in the middle of the long periods of the periodic table. Usage varies, but most commonly the transition elements are taken to include those from scandium to zinc in the first long period, from yttrium to cadmium in the second, and from lanthanum to mercury (excluding the 14 rare-earth metals from cerium to lutecium) in the third.

transition point

A single point at which different phases of matter are capable of existing together in equilibrium. Syn: inversion point.

transition temperature

The temperature at which the change from tough to brittle fracture occurs in a notched bar impact test, or sometimes in other forms of test, e.g., notched tensile test. Syn: inversion point.


One who operates a surveyor's transit. The person need not necessarily be a graduate engineer.

translational fault

A fault in which there has been translational movement and no rotational component of movement; dip in the two walls remains the same. It can be strictly applied only to segments of faults. Syn: translatory fault.

translational movement

Apparent fault-block displacement in which the blocks have not rotated relative to one another, so that features that were parallel before movement remain so afterwards. CF: rotational movement. See also: translational fault. Less-preferred syn: translatory movement.

translation lattice

See: crystal lattice.

translatory fault

See: translational fault.


A term used to describe mineral crystals sufficiently transparent to transmit light. Also called subtransparency. CF: transparency.


The optical property of a mineral to transmit light without objects being visible. CF: opaque.

translucent attritus

This term was first used by R. Thiessen in 1930 referring to the attritus of ordinary humic coal, which is ordinarily composed largely of transparent humic matter, with spores, cuticles, resins, and opaque matter in minor proportions. Translucent attritus consists of the complex residual organic matter, exclusive of anthraxylon, in bituminous lower rank coal that transmits light in thin section. The following macerals of the Stopes-Heerlen nomenclature are included in translucent attritus: vitrinite less than 14 mu m thick; sporinite; cutinite; alginite; resinite; and those parts of semifusinite, micrinite, and sclerotinite that are weakly reflecting, that is semitranslucent. Translucent attritus is a collective term and is not comparable with any of the microlithotypes of the European system of nomenclature.

translucent glass

Glass that will admit rays of light to pass but through which objects cannot be seen.

translucent humic degradation matter

Transparent humic matter consisting of irregular particles varying greatly in shape and size. Although rounded or ovoid particles are not rare, humic matter is mostly flattened in form and usually of frayed or tattered appearance. The particles are of the same deep red color as the anthraxylon strips, becoming lighter in thinner sections. Syn: THDM.


Term used to describe the ability of a system either to amplify or to suppress an input vibration. It is the ratio of the response amplitude of the system in steady-state forced vibration to the excitation amplitude. The ratio may be between forces, displacements, velocities, or accelerations.


A mechanism that provides a variety of gear ratios for different load conditions, speed, or direction of rotation.

transmission reversing

A transmission that has only a forward and reverse shift.


An instrument that measures the capability of a fluid to transmit light; esp. one that measures the turbidity of water by determining the percent transmission of a light beam. See also: turbidimeter.


Rate of heat flow per unit area per unit temperature difference.

transmitted light

Light that has passed through an object, as distinguished from light reflected from a surface. The nonopaque minerals in rocks are commonly studied in transmitted plane-polarized light for characterization and identification by use of a polarized-light microscope. Gems are usually examined for imperfections by transmitted light. CF: birefringence; index of refraction.


The transformation of one element into another. Radioactive decay is an example. Transmutation can also be accomplished by bombardment of atoms with high-speed particles.


In alchemy, the transformation of baser metals into more precious metals.


The property of a mineral to transmit light in part of the visible spectrum while being opaque in another. CF: opaque.


a. The degree to which visible light is transmitted through a solid. A mineral is termed transparent if objects can be clearly seen through it, as through glass; e.g., rock crystal (quartz), selenite (gypsum), Iceland spar (calcite), and gem diamond. Syn: diaphaneity. CF: translucency; opaque.

b. The capacity of seawater to transmit light; the depth to which water is transparent may be measured by use of a Secchi disc. c. A positive image, either black and white or in color, on a clear base (glass or film), intended to be viewed by transmitted light; a diapositive.


a. Permitting the passage of electromagnetic radiation.

b. Things that may be seen through; e.g., rock crystal (quartz), Iceland spar (calcite), selenite (gypsum). CF: opaque.

transparent glass

Glass through which objects can be seen.


An automated receiver and/or transmitter for transmitting signals when triggered by an interrogating signal.


a. A mining term used to cover vehicular transport, hydraulic transport, and conveyors. See also: conveyor; haulage; hydraulic pipe transport.

b. Syn: transportation. The term is favored in British usage, and often occurs in combined terms such as sediment transport and mass transport.

transportable equipment

Machines or equipment that can be moved from one part of a mine to another by mechanical means, such as but not by self-propulsion, on a track, or on attached wheels. See also: mobile equipment.

transportable substation

A transformer equipped with switchgear and mounted upon wheels or skids. Syn: portable substation.


a. In geology, the shifting of material from one place to another on the Earth's surface by moving water, ice, or air. The carriage of mud and dissolved salts by rivers, the passage of a dust-laden whirlwind across a desert, the inland march of sand dunes from a seashore, and the creeping movement of rocks on a glacier are all examples of transportation. See also: transport.

b. The hauling or moving from one place to another of material, such as ore, coal, rock, etc.

transport controller

A person stationed in a central position, at a large opencast pit or quarry, to observe all the excavations. By means of signals, the individual is informed when and where vehicles or cars are required and can instruct the lorry or locomotive drivers accordingly.

transported gossan

Some transported gossans are simply colluvial accumulations of fragments of normal gossan that have moved down the slope from the site of weathering. Another variety of an entirely different origin is effectively a fossil spring or seepage deposit, where at one time iron-rich ground water has precipitated massive limonite at or near the daylight surface.

transport number

In electrolysis, a proportional fall in the number of ions concentrated at an electrode n=loss of concentration at cathode, and/or loss at cathode and anode. This phenomenon is caused by differences in the rate of travel of various species of ion.


a. Of, or pertaining to, radioactive substances produced by bombarding uranium with neutrons.

b. Having an atomic number higher than that of uranium; having an atomic number higher than 92.

Transvaal emerald

See: African emerald.

Transvaal garnet

A green garnet, possibly grossular or a variety of andradite.

transverse fault

A fault that strikes obliquely or perpendicular to the general structural trend of the region. See also: transcurrent fault.

transverse gallery

An auxiliary crosscut made in thick deposits across an orebody for the purpose of dividing it into sections along strike. It is used only a short time and runs across the thickness of the deposit only.

transverse joint

A joint that is transverse to the strike of the strata or schistosity.

transverse loading

The loading on a beam.

transverse pitch

The lateral distance between the center lines of each strand of a multiple-strand chain, or between the tooth profiles on a sprocket for a multiple-strand roller chain.

transverse riffles

See: Hungarian riffles.

transverse slicing with caving

See: top slicing and cover caving.

transverse strength

a. A measure of the capability of a stone bar (or beam) supported at its ends to bear a weight or load at its center.

b. The strength of a specimen tested in transverse bending; normally synonymous with modulus of rupture but also used to refer to breaking load.

transverse thrust

See: transcurrent fault.

transverse trace

A trace on the ground motion record representing the component of motion in a horizontal plane at a right angle to the seismic wave travel direction.

transverse ventilation

See: peripheral ventilation.

transverse wave

a. In seismology, a wave motion in which the motion of the particles, or the entity that vibrates, is perpendicular to the direction of progression of the wave train.

b. In geophysics, a body seismic wave advancing by shearing displacements. c. A wave in which the direction of propagation of the wave is normal to the displacements of the medium; e.g., a vibrating string. The gravity wave in which fluid parcels move in circular orbits is an example of a mixed transverse-longitudinal wave. The Rossby wave is also mixed, except in the case of zero current speed, when it is a transverse wave. Syn: distortional wave; secondary wave. See also: S wave.

transverse with filling

See: overhand stoping.


a. Any dark-colored fine-grained nongranitic rock, such as a basalt, peridotite, diabase, or fine-grained gabbro; also applied to any such rock used as crushed stone. Syn: trapp; traprock; trappide. CF: whinstone.

b. A device for separating suspended sediment from flowing water; e.g., a sand trap. c. A door used for cutting off a ventilating current and that is occasionally opened for haulage or passage. See also: trapdoor. d. A device to separate denser material from less-dense material, such as entrained water in a stream or a compressed-air line. e. That portion of any mass of porous, permeable rock that is sealed on top and down the sides by relatively nonporous and impermeable rock and that lies above the intersection of a horizontal plane passing through the lowest point of complete sealing.

trap cut

A gem with a row or rows of steplike facets around the table and culet (or small lower terminus of the gem, parallel to the table), or around the culet alone. See also: step cut.


a. A door in a mine passage to regulate or direct the ventilating current. Also called weather door. See also: trap. Syn: mine door.

b. See: air door.


a. An isometric crystal form of 24 faces, each face of which is ideally a four-sided figure having no two sides parallel, or a trapezium. Syn: leucitohedron.

b. A crystal form consisting of six, eight, or twelve faces, half of which above are offset from the other half below. Each face is, ideally, a trapezium. The tetragonal and hexagonal forms may be right- or left-handed.


A quadrilateral that has only two sides parallel.

trapezoidal rule

A rule for estimating the area of an irregular figure by dividing it into parallel strips of equal width, each strip being a trapezium. See also: Simpson's rule.


See: trap.


a. An employee, normally an apprentice, used to open and close mine doors. Also called trapper boy; nipper; door tender; doorman. Syn: door boy.

b. An employee who assists the dispatcher by throwing switches and attending telephone at an inside station.

trapper boy

See: trapper.


See: trap.

trap points

Points placed on a railway line to derail a train that has been incorrectly signaled.


See: trap.

trash screen

Protective screen for removing detritus from the pulp stream ahead of a processing unit.


A common name in the older literature for unwelded massive ash and pumice-flow deposits. Trass has been used in the production of pozzolan cement. CF: ignimbrite. Syn: amause.

traveling angle of draw

The angle of draw advancing with a moving face.

traveling apron

See: apron.

traveling block

a. The movable unit, consisting of sheaves, frame, clevis, and/or hook, connected to, and hoisted or lowered with, the load in a block-and-tackle system. Also called floating block; running block.

b. The pulley block that hangs below the crown block and is used for lifting the drilling column. c. A frame for a sheave or a set of sheaves that slides in a track. Syn: traveling sheave.

traveling compartment

The section of a mine shaft used for raising and lowering miners.

traveling gantry

A movable gantry built on wheels for traveling on rails and supporting a hoisting device.

traveling road

A roadway used by miners for walking to and from the face; i.e., from the shaft bottom or main entry to the workings and back. Syn: traveling way.

traveling sheave

A sheave block that slides in a track. See also: traveling block.

traveling way

See: traveling road.

traveling weight

The portion of the overlying strata at the coal face that is supported and controlled by face supports. This weight "advances" as the face line moves forward. See also: underweight.


a. A sequence or system of measured lengths and directions of straight lines connecting a series of surveyed points (or stations) on the Earth's surface, obtained by or from field measurements, and used in determining the relative positions of the points (or stations).

b. A line surveyed across a plot of ground. c. To make a traverse; to carry out a traverse survey. See also: traverse survey. d. A vein or fissure in a rock, running obliquely and in a transverse direction. e. A line across a thin section or other sample along which grains of various minerals are counted or measured.


A platform superimposed upon or forming part of the rail track that is free to roll or slide sideways so that a car can be moved bodily from one track to another parallel to it. See also: inclined traverser.

traverser system

The basic idea of this system is to confine the mine-car circuit to the smallest possible compass near the mine shaft. This avoids locking up cars on the surface that are better employed underground and reduces labor requirements. In this system, instead of the use of shunt backs on car circuits, the direction of car travel is changed by running onto a portable platform that then moves the car bodily in a transverse direction. The system can be applied, in conjunction with the necessary lifts, to multideck cages. This system may be operated electrically, hydraulically, or pneumatically.

traverse survey

A survey in which a series of lines joined end to end are completely determined as to length and direction, these lines being often used as a basis for triangulation. It is used esp. for long narrow strips of land (such as for railroads) and for underground surveys. Syn: traverse.

traverse tables

Published tables giving the differences of latitude and departure for different angles.

traversing method

One of three recognized methods for determining the average velocity of airflow along a mine roadway by an anemometer. This is the general routine procedure applied when measuring air velocities in mine roadways. While the instrument is running, it is slowly and steadily moved up and down a series of imagined vertical lines, so as to cover equal areas in equal time. The total period is usually 1 min for a medium-sized roadway. The integrated reading is then the mean velocity for that section. CF: division method; single-spot method.


a. A dense, finely crystalline, massive or concretionary limestone; generally white, tan, or cream; commonly having a fibrous or concentric structure and splintery fracture; formed by rapid chemical precipitation of calcium carbonate from solution in surface and ground waters, such as by agitation of stream water or by evaporation around the mouth or in the conduit of a spring, esp. a hot spring. It also occurs in limestone caves, where it forms stalactites, stalagmites, and other deposits; as a vein filling; along faults; and in soil crusts. The spongy or less compact variety is tufa. See also: cave onyx; onyx; onyx marble. Syn: calcareous sinter; calc-sinter.

b. A term that has been applied to any cave deposit or calcium carbonate. c. A term used inappropriately as a syn. of kankar. d. Etymol. Italian tivertino from the old Roman name of Tivoli, a town near Rome, where travertine forms an extensive deposit. Also spelled travertin. Syn: travertine marble.

travertine marble

See: travertine.


A small truck or car conveying material about a furnace or iron mill; sometimes applied to trucks, in mines, etc. See also: trolley.


a. A car, carrier, or pallet, usually suspended from the moving element of a conveyor.

b. A section of gravity conveyor, chain conveyor, or shaker conveyor. See also: pan; trough. Syn: tray carrier.

tray carrier

See: tray.

tray thickener

A drying unit that differs from the ordinary round tank in that it houses several horizontal trays that divide it into compartments. Each has its own set of rakes and its own underflow for settled material and peripheral overflow. Used where space is limited or in subarctic conditions that call for antifreeze housing.


a. The ground contact surface on a tire or a track shoe.

b. Occasionally, a high-friction lagging on a belt pulley. c. The pit in which brickmakers soak their clay before putting it into the pug mill.

tread tractor

A form of locomotive that is serviceable over rough roads. A trailer, with capacity up to 16 yd (super 3) (12.2 m (super 3) ), with bottom discharge or two-way side discharge is used with the tractor. The maximum speed is about 6 m/h.

treasure box

A pocket of very rich ore.

treated stone

A gemstone that has been heated, stained, oiled, or coated; treated by various types of irradiation, in order to improve or otherwise alter its color; or laser-drilled to make flaws inconspicuous. Also, a stone that has been preserved from dehydration, such as an opal whose cracks have been filled with oil or other liquid; or one in which special effects have been produced; e.g., amber with "spangles" (tension cracks). See also: altered stone.


The reduction of ores by any process whereby the valuable constituent is recovered.


Three standard lengths of drill rod or drill pipe connected together and handled and stacked in a drill tripod or derrick as a unit length of rod on borehole round trips. Also incorrectly spelled thribble; thrible; tribble; trible. See also: stand; rod stand.

treble coursing

In mining, the system of dividing a ventilating current into three coursings.


A trigonal mineral, AgAsS (sub 2) ; forms minute scarlet-vermillion rhombohedral crystals; at Binenthal, Switzerland.


a. Visible projection of electrodeposited metal formed at a site of high current density.

b. A thick log used as a prop in heavy ground. A prop, leg, or puncheon. See also: treed. c. The fulcrum for the lever used in boring. d. A treelike aggregate of crystals, which forms from solution on a suspended substrate that induces crystallization.

tree agate

A moss agate with dendritic markings resembling trees. Syn: tree stone.


Supported by props, such as a mine roof. See also: tree.


See: trilling.


A hardwood plug drilled so as to allow a track spike to be driven through it into a timber sleeper.

tree ore

A high-grade uranium ore consisting of buried carbon trash that has been replaced or enriched with uranium-bearing solutions.

tree stone

See: tree agate.


A monoclinic mineral, 2[Ca (sub 2) Mg (sub 5) Si (sub 8) O (sub 22) (OH) (sub 2) ] ; amphibole group with magnesium replaced by iron, and silicon by aluminum toward actinolite; white to green; long-bladed or stout prismatic crystals; may show columnar, fibrous, or granular masses or compact aggregates; in low-grade metamorphic rocks such as dolomitic limestones and talc schists; the nephrite variety is the gemstone jade; the asbestiform variety is byssolite. CF: actinolite.


Pertaining to or characterized by the presence of tremolite, as tremolitic marble.

tremor tract

a. An area of intensely jumbled coal and associated beds. The contortions contain sharp folds, thrusts, and glides. The mode or origin is controversial. A theory that has gained some favor is that the disturbance was initiated by a seismic shock, causing the coal seam and beds to crack and heave. Later, lateral forces appear to have produced the final complicated structures.

b. In coal mining, an area of complex folding, faulting, and gliding of coal seams and associated rocks. It may be formed by seismic shocks during the deposit's semicompacted state.


a. A long, straight, commonly U-shaped valley or depression between two mountain ranges.

b. A narrow, steep-sided canyon, gully, or other depression eroded by a stream. c. Any long, narrow cut or excavation produced naturally in the Earth's surface by erosion or tectonic movements. Also, a similar feature produced artificially, such as a ditch dug in prospecting for minerals. d. An elongated but proportionally narrow depression, with steeply sloping longitudinal borders, one of which (the continental) rises higher than the other (the oceanic). Trenches are the ends of unsymmetrical basins and lie beside the continental border or island chains. Syn: marginal trench. e. A long but narrow depression of the deep-sea floor having relatively steep sides. f. A long, narrow, intermontane depression occupied by two or more streams (whether expanded into lakes or not), alternately draining the depression in opposite directions. g. A narrow ditch. h. In geological exploration, a narrow, shallow ditch cut across a mineral deposit to obtain samples or to observe character. i. A long, narrow excavation in the ground, as a trench dug for the laying of pipes. j. A temporary scar in which a conduit is placed and then covered over. CF: ditch.

trench excavation

Excavation in which the width of operations and, generally, the depth are limited. Trenching may be performed in any soil and will sometimes fall into the category of limited-area, vertical excavation.

trench excavator

A self-propelled machine generally mounted on crawler tracks designed for digging trenches or ditches. It is equipped with either a bucket ladder or buckets mounted around the periphery of a circular wheel.


See: ripper.

trench sampling

A slight refinement of grab sampling in which the material to be sampled is spread out flat and channeled in one direction with a shovel, and the material for the sample is taken at regular intervals along the channel. The procedure is repeated with several other channels in different directions until a sample of the proper size has been secured. Also called channel sampling.


a. A general term for the direction or bearing of the outcrop of a geological feature of any dimension, such as a layer, vein, orebody, fold, or orogenic belt. CF: strike. Syn: direction.

b. The direction or rate of increase or decrease in magnitude of the individual members of a time series of data when random fluctuations of individual members are disregarded; the general movement through a sufficiently long period of time of some statistical progressive change. c. The direction or bearing of a bed, dike, sill, etc., or of the intersection of the plane of a bed, dike, joint, fault, or other structural feature with the surface of the ground. d. The direction or bearing of a fold or series of folds in rocks, of the axes of the folds, of subsurface structures, of oriented or elongated structures indicated by geological surveys, or of topographic features that are consequent on the geologic structure. (As used in either sense, the trend may or may not coincide with the strike, depending on the structural relations at the place of observation.) CF: trace.

trent agitator

An agitator with paddle-wheel-type arms; they are hollow, and the pulp solution or air is discharged from nozzles on these arms, thus causing the stirrer to rotate.


a. A subdivision of the American Ordovician sometimes considered as the equivalent of the whole Middle Ordovician and sometimes restricted to a portion of this series.

b. Formerly, a division of the lower Silurian.

Trent process

Agglomeration process sometimes used in coal cleaning and briquetting. Raw coal crushed to minus 65 mesh is agitated with water and oil. Coal agglomerates and ash-forming fraction are removed in aqueous solution.


a. A boring tool once used in the Kind-Chaudron shaft-sinking method.

b. A boring machine used for shaft sinking through water-bearing strata.


A cutter loader for continuous mining in longwall faces. Its main cutting unit is the trepanner wheel with cutting arms, one at each end of the machine to enable it to cut in both directions on the face. Also fitted are a vertical, back-shearing jib; a floor-cutting jib, duplicated to enable cutting in either direction; and, if necessary, a roof-cutting disk. The machine is used in conjunction with an armored flexible conveyor on a prop-free front face; suitable for seams between 3 ft and 4 ft (0.9 m and 1.2 m) thick, although it can work in thicker seams if the top coal falls freely.


A type of boring in which an annular cut is made into a solid material, with the coincidental formation of a plug or solid cylinder.

trepan shearer

A cutter loader in which the trepanner head is incorporated into the shearer-loader while the cutting drum is retained to dress the floor and back of the cut.


Working coal from the property or take of another coal mine owner. See also: encroachment. Syn: bootleg.


a. A bridge, usually of timber or steel, that has a number of closely spaced supports between abutments.

b. A bent of timber, reinforced concrete, or steel, supporting a temporary or permanent structure.


Person who unloads coke, limestone, and ore, and keeps bins poked down.


Allowance to purchaser for waste.


An isometric mineral, NiFe (sub 2) O (sub 4) ; magnetite series of the spinel group; black with greenish tint; at Barberton, Transvaal, South Africa.


In crystallography, an element of symmetry characterized by a rotational axis requiring three operations to return to identity. Isometric symmetry contains four diagonal triads; trigonal symmetry requires a unique triad. CF: threefold. See also: trigonal.

trial face

See: experimental face.

trial pit

A shallow hole, 2 to 3 ft (0.6 to 0.9 m) in diameter, put down to test shallow minerals or to establish the nature and thickness of superficial deposits and depth to bedrock. See also: test pit; pit sampling.

trial shots

The experimental shots and rounds fired in a sinking pit, tunnel, opencast, or quarry to determine the best drill-hole pattern to use. This is carried out when hard rocks are exposed.


A chemical compound crystallizing in three different crystal structures.

triangle cut

The characteristic feature of this cut lies in the fact that the drill holes are arranged in zigzag. In this way a larger opening is obtained because the drill holes can break out between the preceding rows. Each vertical row of holes breaks out a layer. If the front holes do not break out to the full depth, the burnt-out holes indicate the direction of break for the following row of holes since the holes are arranged in zigzag. The name, triangle cut, is due to the distribution of the holes at the working face and the form of the initial opening.

triangle shooting

A refraction type of seismic shooting used to facilitate the separation of intercept times into constituent delay times. Three profiles can be laid out as sides of a triangle. If intercept times are obtained at each of the vertices of the triangle from shots at the other two vertices, one can solve for the delay times at the three corners. Delay times along the sides of the triangle can be determined by taking differentials in the intercept times with respect to the delay times established at the vertices.

triangular core

The strand core of a flattened strand rope.

triangular facet

A physiographic feature having a broad base and an apex pointing upward; specif. the face on the end of a faceted spur, usually a remnant of a fault plane at the base of a block mountain. A triangular facet may also form by wave erosion of a mountain front or by glacial truncation of a spur. Syn: spur-end facet.

triangular method

A method of ore reserve estimation based on the assumption that a linear relationship exists between grade difference and the distance between all drill holes.

triangular texture

In mineral deposits, texture produced when exsolved or replacement mineral crystals are arranged in a triangular pattern, following the crystallographic directions of the host mineral.


To divide into triangles; esp. to use, survey, map, or determine by triangulation. Etymol: back-formation from triangulation.


a. A trigonometric operation for finding the directions and distances to and the coordinates of a point by means of bearings from two fixed points a known distance apart; specif. a method of surveying in which the stations are points on the ground at the vertices of a chain or network of triangles, whose angles are measured instrumentally, and whose sides are derived by computation from selected sides or base lines, the lengths of which are obtained by direct measurement on the ground or by computation from other triangles. Triangulation is generally used where the area surveyed is large and requires the use of geodetic methods. CF: trilateration. Syn: trigonometrical survey.

b. The network or system of triangles into which any part of the Earth's surface is divided in a trigonometric survey.

triaxial compression test

A test in which a cylindrical specimen of rock encased in an impervious membrane is subjected to a confining pressure and then loaded axially to failure. See also: unconfined compression test. Syn: triaxial shear test.

triaxial shear test

See: triaxial compression test.


A subdivision of the rock association or kindred. A tribe is made up of clans. See also: rock association.


Two chemically dissimilar metals in mutual electrical contact. The friction produced by the mechanical agitation of the two members of the couple results in the flow of an electric current. The power of a tribocouple is the magnitude of the current that it will generate under specified conditions of friction.

Triboelectrostatic separation process

An electrostatic process under development, in which fine-size dry coal is blown rapidly past a copper baffling device that imparts positive triboelectric charges on the coal and negative charges on the associated mineral matter. The material is introduced into an electrostatic separator, where it is separated.


a. The property of some specimens of zinc sulfide of emitting sparks when scratched.

b. Luminescence in which electrons in a trapped state are released by abrasion or crushing. CF: luminescence.


a. Three leveling screws and footplate used to attach a theodolite or surveyor's level to its tripod, level the instrument, and center it precisely over its mark.

b. The frame below a theodolite on which three foot screws are mounted. See also: limb.


See: bromoform.

tribute work

In mining, work on shares.


a. A system under which a syndicate of miners delivers coal at the pithead at an agreed price. This system may be used where ore deposits are too small and scattered to conduct normal mining activities. "Tributors" work and deliver their ore to the owner and receive payment based on the ore's ascertained value.

b. Working on a sharing basis.

tricalcium pentaluminate

A compound, 3CaO.5Al (sub 2) O (sub 3) , formerly believed to be present in high-alumina hydraulic cement. It is now known that a melt of this composition consists of a mixture of CaO.2Al (sub 2) O (sub 3) and CaO.Al (sub 2) O (sub 3) , the latter compound being responsible for the hydraulic properties.

tricalcium silicate

3CAO.SiO (sub 2) ; dissociates at approx. 1,900 degrees C to form CaO and 2CaO.SiO (sub 2) . This compound is the principal cementing constitutent of Portland cement, small quantities of MgO and Al (sub 2) O (sub 3) usually being present in solid solution. Tricalcium silicate is also present in stabilized dolomite refractories.


A former name for tyrolite. See also: tyrolite.


A straight or curved hairlike crystallite, usually black. Trichites occur singly or radially arranged in clusters and are found in glassy igneous rocks.


Colorless; stable; low-boiling; heavy; mobile; toxic; liquid; CHCl:CCl (sub 2) .


Characteristic of a crystal showing three different colors in transmitted light; limited to crystallization in the orthorhombic, monoclinic, and triclinic systems. CF: pleochroism; dichroism.

trickle drain

A pond overflow pipe set vertically with its open top level with the water surface.

trickle scale

Scale that has become detached from a pack of sheets in pack rolling, trickling in between the pack and becoming embedded in the surface of the sheets during further rolling.


a. In crystallography, periodicity requiring three crystal axes having no further constraint on the interaxial angles designated alpha, beta, and gamma.

b. The least symmetric of the seven (or six) crystal systems, requiring all three axial vectors a, b, and c and three interaxial angles alpha , beta , and gamma as lattice parameters. Of its two crystal classes, one has a center of symmetry and the other does not. Feldspars and axinites crystallize in the triclinic system. Syn: anorthic (obsolete); triclinic system.

triclinic block

In quarrying, a term applied to a block of stone bounded by three pairs of parallel faces, none of which intersect at right angles.

triclinic crystal

Crystal having no symmetry elements, or only an inverse center. The typical crystal has three unequal axes, no two of which are perpendicular.

triclinic system

See: triclinic.

tricone bit

A roller bit having three cone-shaped cutters in the head of the bit. See also: roller bit. Syn: tricone roller bit.

tricone roller bit

See: tricone bit.


See: tridymite.


A monoclinic and triclinic mineral, 4[SiO (sub 2) ] ; pseudohexagonal; polymorphous with coesite, cristobalite, quartz, and stishovite; colorless to white; in felsic volcanics and refractories. Also spelled tridimite.

Triger process

A method of sinking through water-bearing ground in which a shaft is lined with tubbing and provided with an air lock so that work proceeds under air pressure. CF: Kind-Chaudron process.

trigger circuit

A circuit having a number of states of electrical condition (which are either stable or quasi-stable) or that is unstable with at least one stable state and so designed that a desired transition can be initiated by the application of a suitable trigger excitation. By quasi-stable state is meant a state that persists during the time of interest.

trigger effect

When rock is subjected to increasing stresses there comes a time when it is on the point of failure. In some circumstances it may remain at that point for a considerable time. Any small external influence, such as a seismic wave, may then be sufficient to precipitate the failure. This is known as the trigger effect.


Term applied to any number of things that may initiate or trigger rock bursts. Such triggers include blasting, changes of temperature, sudden influxes of water, and even rock bursts themselves, which sometimes act as a trigger impulse to initiate a second burst.


a. Describes a crystal form or structure with a unique triad of symmetry.

b. A symmetry operation requiring three repetitions to return to identity. Syn: triad. c. Characteristic of, pertaining to, or belonging in the trigonal system or in the rhombohedral division of the hexagonal system. (Not all trigonal point groups may be characterized by rhombohedral axes, hence the incongruence between the trigonal system and the rhombohedral division of the hexagonal system.) CF: rhombohedral division; hexagonal system.

trigonal coordination

In a crystal structure, a cation with three anions around it at the points of a triangle, e.g., C in a CO (sub 3) (super 2-) group.

trigonal system

In assigning point groups to seven crystal systems, the trigonal system is characterized by a unique triad, that element of rotational symmetry for which three operations of 120 degrees return a lattice to identity. CF: rhombohedral division; hexagonal system.


A monoclinic mineral, Pb (sub 3) Mn(AsO (sub 3) ) (sub 2) (AsO (sub 2) OH); forms sulfur-yellow triangular wedge-shaped crystals; at Laangban, Sweden.

trigonometrical leveling

Basically this method consists of determining the vertical heights by measurement of distances and angles of inclination. Angles of inclination are measured either by hand instruments or more accurately by theodolite.

trigonometrical survey

See: triangulation.


Measurement of three-angled figures, or measurement by use of three-angled figures.


A hydrous calcium carbonate, CaCO (sub 3) .3H (sub 2) O . A moldlike incrustation on chalk marl. From Nova-Alexandria, Poland.


A hexagonal mineral, (K,Na)AlSiO (sub 4) ; polymorphous with kaliophilite, kalsilite, and panunzite.


A method of surveying in which the lengths of the three sides of a series of touching or overlapping triangles are measured (usually by electronic methods) and the angles are computed from the measured lengths. CF: triangulation.


See: trilling.


A cyclic crystal twin consisting of three individuals. CF: fourling; fiveling; eightling. Syn: treeling; trill. See also: threeling.


A primitive, extinct crustacean, occurring throughout the Paleozoic and abundant in the earlier Paleozoic periods, characterized by a segmented body divided by longitudinal grooves into three lobes.


A monoclinic mineral, CaMn (sub 2) Be (sub 3) (SiO (sub 4) ) (sub 3) .


A solid figure in which the three axes are all unequal, but intersect one another at right angles. Syn: orthorhombic.

trim holes

Unloaded drill holes closely spaced along a line to limit the breakage of a blast. Syn: relief holes.


a. A shothole bored slightly outward to trim the drivage to the shape required.

b. An apparatus for trimming a pile of coal into a regular form (such as a cone or prism). c. One who uses a shovel to distribute loose material--such as coal, rubbish, sand, or other substances--in railroad cars or holds of ships and barges during or after loading. May be designated according to material trimmed, such as a coal trimmer.

trimmer conveyor

A self-contained, light-weight portable conveyor, usually of the belt type, for use in unloading and delivering bulk materials from trucks to domestic storage, and for trimming bulk materials in bins or piles. See also: portable conveyor.

trimmer holes

These complete the breaking out of the ground. The positioning and number of trimmer shots are governed by the size of the drift, the hardness of the ground, and the fragmentation required for the loading-out method to be adopted.


a. The shotholes drilled around the periphery of a shaft or tunnel that break or trim the sides of the excavation to the shape and size required. See also: cut holes.

b. The top row of holes in a tunnel face.

trimming shed

See: mica house.


The property of a chemical compound to crystallize in one of three different crystal structures. CF: dimorphism; polymorphism.


A chemical compound that may crystallize in one of three different crystal structures.


Dense asphaltic petroleum containing 9% sulfur.

trinitrate glycerol

See: nitroglycerin.


See: nitroglycerin.

trinitrotoluene-ammonium nitrate explosive

An explosive containing ammonium nitrate sensitized with trinitrotoluene. A proportion of aluminum powder or calcium silicide may be added to increase power and sensitiveness.


A resinous substance occurring in large amorphous masses of a hyacinth-red to chestnut-brown color in brown coal near Albona, Istria (former Yugoslavia). Resembles tasmanite in composition.


Pertaining to a layered-mineral structure of the kaolinite-serpentine, talc-pyrophyllite, mica, or chlorite groups in which all three of the positions with octahedral coordination are occupied, mainly by divalent cations, such as Mg, or by a mix of monovalent and trivalent cations, such as Li and Al. CF: dioctahedral.


a. A small train of mine cars.

b. The number of cars moved at one time by a transportation unit. c. The operation in rotary drilling of pulling out (trip out) and running in (trip in) the drill string, as required to replace a worn bit, extract a core, or recover a fish. Syn: round trip. d. An automatic arrangement for dumping cars; a tipper, a kickup. e. A release catch.

trip change

A term used in mine transportation for the period during which the loads (loaded mine cars) are taken away and a fresh trip of empties is brought back. This period is known as trip change in contrast to car change. In this interval a great deal of potential loading time can be lost.

trip coil

A device for opening protective equipment or a circuit breaker, operated by a solenoid.


a. A mineral form with the outward appearance of tripe or intestines, e.g., stalactitic calcite, crumpled gypsum laminae, contorted concretionary anhydrite, barite. Also spelled tripe stone.

b. Stalactite resembling intestines. c. A variety of gypsum formed of crumpled, alternating laminae of pure white gypsum and gray argillaceous gypsum. d. A contorted concretionary variety of anhydrite.

trip hammer

A power hammer operated by a tripping mechanism that causes the hammer to drop.


A former name for spodumene.


An orthorhombic mineral, 4[LiFe (super 2+) (PO (sub 4) )] , with manganese replacing iron toward lithiophilite; bluish to greenish gray; in granite pegmatites.

trip lamp

A removable self-contained mine lamp, designed for marking the rear end of a train (trip) of mine cars.

triple entry

A system of opening a mine by driving three parallel entries for the main entries. See also: main entry.

triple-entry room-and-pillar mining

See: room-and-pillar.

triple point

An invariant point at which three phases coexist in a unary system. When not otherwise specified, it usually refers to the coexistence of solid, liquid, and vapor of a pure substance.


An assembled stone of two main parts of gem materials bonded by a layer of cement or other thin substance (the third part of the triplet), which gives color to the assemblage. CF: doublet; emerald triplet.


A name for emerald-colored beryl triplet. See also: emerald triplet.

triple-tube core barrel

A special core barrel used to take soil samples, as in foundation testing. The inner tube is swivel mounted and nonrotating and extends through, and a short distance beyond, the bit. Hence, the bit only cuts clearance for the outer tube or core-barrel assembly, and the core taken by the inner tube is cut by a spudding action. The triple or core tube is mounted inside the inner tube to receive the core and is split longitudinally to facilitate removal of the core. Also called clay barrel.

Triplex glass

A patented form of laminated glass. See also: safety glass.


A method of steelmaking that involves the use of three processes, e.g., a sequence of melting in a cupola, blowing in a Bessemer converter, and finishing in a basic electric furnace, or a combination of the acid Bessemer converter, the basic open-hearth furnace, and the basic electric furnace.

triplex pump

A positive-displacement piston pump having three water cylinders mounted side by side. It may be either a single- or double-action type. CF: duplex pump.


A monoclinic mineral, 8[(Mn,Fe,Mg,Ca) (sub 2) (PO (sub 4) )(F,OH)] ; brown; forms fibrous masses; in granite pegmatites. Syn: pitchy iron ore.


A monoclinic mineral, (Mn,Fe) (sub 2) (PO (sub 4) )(OH) ; perfect cleavage.

trip maker

A device to elevate cars on an inclined track as received from a kickback.


A three-legged support for a rock drill, hoisting drum, magnetometer, or any other piece of equipment.


See: diatomite.


A term that has been applied as a syn. of diatomite, in reference to the material from the north African location of Tripoli. It has also been used, less correctly, as a syn. of tripoli. See also: diatomite.


a. A device in the run of a conveyor comprising two free drums around which the belt passes S-fashion.

b. A device for discharging material from a belt conveyor. c. A double pulley that turns a short section of a conveyor belt upside down in order to dump its load into a side chute. d. A device or mechanism that trips, as a device for causing the load on a conveyor to be discharged into a hopper or other receptacle. e. An automatic car dump. f. A device for tipping and dumping the skip at the top of the blast furnace.

tripper man

Person who unloads grain or ore from conveyor belt into bins or processing equipment by operating a tripper. Syn: conveyor-operator tripper; conveyor-tripper operator; spreader operator.


a. The process of pulling and/or lowering drill-string equipment in a borehole.

b. To open a latch or locking device, thereby allowing a door or gate to open to empty the contents of a skip, bailer, etc.


A tetragonal mineral, CuAs (super +3) (sub 2) O (sub 4) ; excellent prismatic cleavage permitting crystals to be broken into flexible fibers; blue-green; at Atacama, Chile.

trip recorder

See: hoist trip recorder.

trip sender

In bituminous coal mining, a laborer who switches cars to various tracks, couples and uncouples trains, and attaches and detaches cars to and from the haulage cable at a mine where there are several sidetracks on the haulageway.


A tetragonal mineral, FeSb (sub 2) O (sub 6) ; forms dull greenish-yellow microcrystalline aggregates; in the cinnabar-bearing gravels of Tripuhy, Ouro Preto, Minas Gerais, Brazil.


In metallurgy, a slag with a silicate degree of 3.

trislope screen

A screen in which each section of the deck is flatter than the preceding one. The rate of feed is reduced on succeeding sections to maintain proper bed depth for rapid stratification. It is designed for fine dry screening of 3/4-in (19-mm) by 0-in, 1/2-in (13-mm) by 0-in, and 1/4-in (6 mm) by 0-in moist coal or other material. See also: varislope screen.


A crystal form of 24 faces in the isometric system with the gross appearance of each face of an octahedron being replaced by three faces arrayed around a diagonal triad. Each face of a trigonal trisoctahedron is an isosceles triangle, while each face of a tetragonal trisoctahedron is a trapezoid. Syn: trapezohedron.

trisodium phosphate

Na (sub 3) PO (sub 4) , a chemical compound used in some enamel frit compositions.


a. An isometric hemihedron included under 12 trapeziform faces; a tetragonal tristetrahedron.

b. An isometric hemihedron included under 12 isoceles triangular faces; a trigonal tristetrahedron.


The radioactive isotope of hydrogen having two neutrons and one proton in the nucleus. Being hydrogen-3, it is heavier than deuterium (heavy hydrogen or hydrogen-2).


A trigonal mineral, (Ce,La,Y,Th) (sub 5) (Si,B,Al) (sub 3) (O,OH,F) (sub 13) (?) ; moderately radioactive; metamict; dark brown; in syenite with leucophanite, analcime, mosandrite, aegirine, and catapleiite. Formerly called spencite.

triton value

The number of grams of TNT required to produce the same angle of recoil of the ballistic mortar as 10 g of the explosive under test.


a. A powder produced from a solid by grinding, usually with the addition of some liquid.

b. To grind to a powder, usually with the addition of some liquid.


Reduction to a fine powder by grinding. Syn: comminution. CF: levigation.


a. Having a valence of 3.

b. Having three valences; e.g., chromium, which has valences of 2, 3, and 6. Syn: tervalent.