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

Los Angeles abrasion testing machine
 * A machine for measuring abrasion resistance or toughness. It consists of a closed hollow steel cylinder 28 in (71.12 cm) in diameter and 20 in (50.8 cm) long mounted for rotation with its axis horizontal. The sample being tested and a charge of steel spheres are tumbled during rotation by an internal shelf.

lose
 * a. Eng. To work a seam of coal, etc., up to where it dies out or is faulted out of sight. This is called "losing the coal."

b. To be unable to work out a pillar on account of thrust, creep, gob fire, etc. c. A pit shaft is said to be "lost" when it has run in or collapsed beyond recovery.

loseyite
 * A monoclinic mineral, (Mn,Zn) (sub 7) (CO (sub 3) ) (sub 2) (OH) (sub 10); soft; bluish white; at Franklin, NJ.

losing iron
 * See: furnace losing-the-iron.

loss of vend
 * Difference between weight of raw coal and that of salable products, expressed as a percentage.

loss on ignition
 * As applied to chemical analyses, the loss in weight that results from heating a sample of material to a high temperature, after preliminary drying at a temperature just above the boiling point of water. The loss in weight upon drying is called free moisture; that which occurs above the boiling point of water, loss on ignition.

lost circulation
 * The condition during rotary drilling when the drilling mud escapes into porous, fractured, or cavernous rocks penetrated by the borehole and does not return to the surface.

lost closure
 * The amount of closure of the walls of a stope that occurs before supports have been placed and begin to oppose that closure.

lost core
 * The portion of a core that is not recovered. It may be the soft rock that crumbles and falls from the core barrel or the solid piece or pieces of core that drop to the bottom of a borehole after slipping out of the core barrel while the drill string is being pulled from the drill hole.

lost corner
 * A corner whose position cannot be determined, beyond reasonable doubt, either from traces of the monument, or by reliable testimony relating to it; and whose location can be restored only by surveying methods and with reference to interdependent existent corners, by mutual agreement of abutters, or by court decision.

lost hole
 * A borehole in which the target could not be reached because of caving, squeezing, loose ground, or inability to recover lost tools or junk.

lost level
 * Corn. A level or gallery driven with an unnecessarily great departure from the horizontal.

lost river
 * a. A dried-up river in an arid region.

b. A river in a karst region that drains into an underground channel.

lost thread method
 * See: string survey.

lost water
 * See: lost circulation.

loudspeaker face telephone
 * An intrinsically safe public address system developed for coal face communications. Up to 20 individual units, each containing a telephone handset and speaker, can be coupled together along the face and gate roads by a five-way cable. Instructions, requests, etc., made into any one of the handsets are broadcast simultaneously over all the loudspeakers. See also: signaling system.

loup
 * The pasty mass of iron produced in a bloomery or puddling furnace. CF: looping.

loupe
 * Any small magnifying glass or lens mounted for use in the hand, held in the eye socket, or attached to spectacles and used to study minerals and rocks. Also spelled lupe, loup, loop.

louver cleaner
 * In ore dressing, smelting, and refining, one who trims carbon anodes and cleans louvers to minimize electrical resistance in magnesium refining cells.

louvers
 * Overlapping and sloping slats arranged to prevent entrance or exit of a portion of an air stream. Louvers are sometimes used as a regulator in place of a sliding or other adjustable door.

love arrows
 * See: fleches d'amour.

love stone
 * See: aventurine.

Love wave
 * a. A transverse wave propagated along the boundary of two elastic media that both have rigidity; i.e., both media must be capable of propagating transverse waves.

b. A surface seismic wave in which the particles of an elastic medium vibrate transverse to the direction of the wave's travel, with no vertical component. c. A type of surface wave having a horizontal particle motion that is transverse to the direction of propagation. Its velocity depends only on density and rigidity modulus, and not on bulk modulus. It is named after A.E.H. Love, the English mathematician who discovered it. Syn: Q wave; Querwellen wave.

lovozerite
 * The mineral group imandrite, kazakovite, koashvite, lovozerite, petarasite, tisinalite, and zirsinalite.

low
 * a. A former stream channel in a coalbed, filled with sandstone, clay, and shale. CF: cutout. See also: washout.

b. A general term for such features as a structural basin, a syncline, a saddle, or a sag. CF: high. Syn: structural low. c. Indicates that a crystal structure is the low-temperature dimorph for the crystal compound.

low-alumina silica brick
 * Special brick in which the total alumina, titania, and alkali are significantly lower than in regular silica brick.

low-angle fault
 * A fault with a dip of 45 degrees or less. CF: high-angle fault.

low bed
 * A machinery trailer with a low deck.

low blast
 * A blast delivered to a smelting furnace at low pressure.

low coal
 * Coal occurring in a thin seam or bed.

low-deflagrating explosive
 * Another name for black powder.

Lowden drier
 * Mechanized drying floor used for ores or concentrates. Reciprocating rakes move the material gently over steel plates heated from below.

low-density explosive
 * Explosive designed for use in mining, where it is required to blast with the least amount of shattering and/or to reduce explosive cost. The density of ordinary explosives may be decreased by (1) loose packing, (2) an alteration in the granular state of the ammonium nitrate, and (3) the impregnation of woodmeal or suitable substitutes. By decreasing the density of an explosive the same weight of explosive is used, but owing to its greater bulk the explosive effects are distributed over a greater area, thus producing a less shattering effect.

low-discharge ball mill
 * One with a substantial downslope between the trunnion-high feed end and the peripheral discharge end. This facilitates the brisk movement of ore through the mill.

low doors
 * Scot. The lowest of two or more landings in a shaft.

low-duty fire clay brick
 * A fire-clay refractory having a pyrometric cone equivalent not lower than 19 and a minimum modulus of rupture of 600 psi (4.1 MPa).

loeweite
 * A trigonal mineral, Na (sub 12) Mg (sub 7) (SO (sub 4) ) (sub 13) .15H (sub 2) O ; white; water soluble. Also spelled loeweite.

lower
 * Pertaining to rocks or strata that are normally below those of later formations of the same subdivision of rocks. The adj. is applied to the name of a chronostratigraphic unit (system, series, stage) to indicate position in the geologic column and corresponds to early as applied to the name of the equivalent geologic-time unit; e.g., rocks of the Lower Jurassic System were formed during the Early Jurassic Period. The initial letter of the term is capitalized to indicate a formal subdivision (e.g., Lower Devonian) and is lowercased to indicate an informal subdivision (e.g., lower Miocene). The informal term may be used where there is no formal subdivision of a system or of a series. CF: upper; middle.

lower break
 * The lower bend of either a terrace or a monocline, also known as the foot or the lower change of dip. See also: foot.

lowering conveyor
 * Any type of vertical conveyor for lowering objects at a controlled speed. See also: arm conveyor; suspended tray conveyor; vertical reciprocating conveyor.

lowering skips
 * Used in some river tipples to let the coal down into the barges. Also known as weigh pans.

lowering tongs
 * Long-handled, plierlike device similar to a certain type of blacksmith tongs used to handle wash or drill rods in place of a safety clamp in shallow borehole drilling. Syn: brown tongs; knife dog.

lower leaf
 * Scot. The lower portion of a seam of coal that is worked in two sections or leaves.

lower limit of flammability
 * The smallest quantity of combustible gas that, when mixed with a given quantity of air (or oxygen), will just support a self-propagating flame.

lower liquid limit
 * In soil mechanics, the moisture content at which soil changes from plastic to liquid.

lower plastic limit
 * Moisture content of soil at which it changes from a plastic to a semisolid state.

lower plate
 * See: footwall.

lowest visible red-heat
 * Common division of the color scale--about 887 degrees F (475 degrees C).

low explosive
 * An explosive in which the change into the gaseous state is effected by burning and not by detonation as with high explosives. Blasting powder (black powder or gunpowder) is the only low explosive in common use. It requires no detonator but is ignited by means of a safety fuse. Also called propellant.

low-freezing dynamites
 * Dynamites made by replacing part of the nitroglycerin of straight dynamites with some ingredient to render the dynamite incapable of freezing under ordinary conditions of use. The freezing point is depressed by adding nitro substitution compounds, such as nitrated sugars, nitrotoluene, nitrated polymerized glycerin, or ethylene glycol dinitrate.

low-freezing explosive
 * See: polar explosive.

low gear
 * a. See: slow gear.

b. Mining and/or drilling operations carried on at a leisurely pace and at less-than-normal output per worker shift. c. When applied to a screwfeed-type drill, the pair of feed gears in the feed mechanism that advances the bit the least amount for each revolution of drill drive rod and/or coupled drill stem. d. When applied to speed at which the drill motor rotates the drill stem, the transmission-gear position giving the lowest number of bit revolutions per minute per engine revolutions per minute; corresponds to low gear in an automobile.

low-grade
 * a. An arbitrary designation of dynamites of less strength than 40%. It has no bearing on the quality of the materials, as they are of as great purity and high quality as the ingredients in a so-called high-grade explosive.

b. Sometimes applied to poor- or low-quality drill diamonds. c. Pertaining to ores that have a relatively low content of metal compared with other richer material from the same general area. Also designates coal high in impurities. Low-grade metamorphism refers to metamorphism at a relatively low temperature and/or pressure. CF: high-grade. d. See: lean ore.

low-grade coal
 * Combustible material that has only limited uses owing to undesirable characteristics (for example, ash content or size).

low-heat cement
 * A cement in which there is only limited generation of heat during setting, achieved by modifying the chemical composition of normal portland cement.

low-heat-duty clay
 * A clay that fuses between 1,520 degrees C and 1,590 degrees C.

low-iron magnesite brick
 * A burned magnesite brick, containing 90% or more of magnesia, and 1.5% to 2.5% iron oxide.

low level
 * Scot. The drift or working that is farthest to the dip; also called laigh level.

low-nitrate barren
 * In uranium leach treatment, the bulk of the barren solution after some 75,700 L of high-nitrate solution have been run through the ion-exchange (IX) column. Low in nitrate and uranium and contains some backwash water.

low powders
 * Explosives containing a small portion of nitroglycerin and a base similar to blasting powder. Intermediate between blasting powder and dynamite in action. See: low-grade.

low-pressure air stower
 * The filling of the waste by means of compressed-air blower. The blower is usually located close to the stowing machine and operated at a pressure below 15 psi (103.4 kPa). For light duties, only one blower is required to operate one stowing machine. For heavier work, or very long lengths of pipeline, two blowers are used in series. The maximum horsepower for two blowers in series does not commonly exceed 200 (149 kW) at large installations. See also: pneumatic stowing.

low-pressure limit
 * The lowest pressure at which flame propagation can be obtained through a combustible-oxidant system at a fixed temperature in a particular chamber.

low quartz
 * Low-temperature quartz; when formed below 573 degrees C, SiO (sub 2) tetrahedra are less symmetrically arranged than at higher temperatures; inversion is reversible. Syn: alpha quartz.

low-rank coals
 * See: rank.

low-rank metamorphism
 * Metamorphism that is accomplished under conditions of low to moderate temperature and pressure. CF: high-rank metamorphism.

low red-heat
 * Temperature of iron at which redness is observable in subdued daylight (525 to 700 degrees C). Bright red heat is in the range 700 to 1,000 degrees C and is followed by orange at 1,000 degrees C, white at 1,300 degrees C, and blue-white at 1,500+ degrees C.

low shaft furnace
 * A short shaft-type blast furnace that can be used to produce pig iron and ferroalloys from low-grade ores, using low-grade fuel. The air blast is often enriched with oxygen. It can also be used for making a variety of other products such as alumina, cement-making slags, and ammonia synthesis gas.

low-temperature carbonization
 * Carbonization carried out at a low temperature (between 500 degrees C and 700 degrees C). During the process, the smoke-producing compounds are driven off as tars and oils and collected as valuable byproducts, leaving a coke with about 10% volatile matter. The coke yield is about 1,400 lb/st (700 kg/t) and is used as a domestic fuel.

low-temperature coke
 * A solid fuel produced by the low-temperature carbonization of coal.

low-temperature incineration method
 * In this method for the determination of incombustible matter, the mine roadway dust (dust containing carbonates) is incinerated at a temperature of not less than 500 degrees C and not more than 530 degrees C until it is constant in weight. This temperature is sufficient to complete the combustion of the organic matter in the dust, but is not high enough to decompose the carbonates. However, this method is unsuitable for dust containing magnesium carbonate because this substance decomposes below 500 degrees C, and therefore a low result for the incombustible matter would be obtained. The moisture content of the sample may be calculated so that an allowance can be made for the weight loss attributed to moisture.

low-tension detonator
 * A detonator requiring a minimum current of 1 A for firing and having a resistance of about 1 Omega.

low-terrace drift
 * Aust. Gravel and shingle in terraces.

low velocity
 * See: velocity.

low-velocity-layer correction
 * See: weathering correction.

low volatile bituminous coal
 * The rank of coal, within the bituminous class of Classification D 388, such that, on the dry and mineral-matter-free basis, the volatile matter content of the coal is greater than 14% but equal to or less than 22% (or the fixed carbon content is equal to or greater than 78% but less than 86%), and the coal commonly agglomerates. CF: bituminous coal.

low voltage
 * In coal mining, 660 V or less. Also called low potential. CF: high voltage; medium voltage.

low working voltage
 * Low working voltage in coal mines is one of the many conditions that must be given continual attention. Loss of voltage means a proportional loss in power. Since the quantity of dc power is obtained by multiplying the number of amperes times the number of volts, it follows that for a given amount of power if the volts are lowered the amperes are increased, and the increase in amperes results in an increase in power loss in the mine circuit. Lower operating voltages result in heavier currents in the dc motor circuits, thus heating the motors, cables, and circuit wiring and causing loss in motor speed, inefficient operation, and increased maintenance cost.

lozenge
 * A form of cut stone produced by the meeting of the skill and star facets on the benzil of brilliants; or by the meeting of the facets in the horizontal ribs of the crown.

lpb
 * To determine the horizontal compass direction that a borehole is trending at a specific depth by means of one of several borehole surveying instruments.

LP delays
 * Long period delays used in delay blasting underground and generally available in intervals of seconds.

lublinite
 * A fibrous variety of calcite.

lubrication
 * The act of applying lubricants. There are two main types of lubricants, solid and liquid. Examples of the solid type are graphite, French chalk, and sulfur. Liquid lubricants are by far the more important, and among these, oils and greases are the most common.

Luce and Rozan process
 * A modification of the Pattinson process whereby the molten lead is stirred by the injection of steam; used in desilverizing base bullion.

lucianite
 * An expansive clay of the smectite(?) group at Santa Lucia, near Mexico, D.F.

lucid attrite
 * Variety of attritus that is transparent in thin section.

lucinite
 * A variety of variscite from Lucin, UT.

Luckiesh-Moss visibility meter
 * This instrument has been used over a wide range of lighting applications. It consists of a pair of similar photographic gradient filters, which increase in density as they are rotated together before the eyes. The filters therefore reduce the apparent brightness of the observed field and at the same time lower the contrast between the object of view and its background.

luckite
 * A manganoan variety of melanterite at the Lucky Boy Mine, Salt Lake County, UT.

lucky stone
 * See: staurolite.

Lueders line
 * Surface markings that result from strain. Sometimes called Hartmann lines; Piobert lines; stretcher strains. See also: slip line.

ludlamite
 * A monoclinic mineral, (Fe,Mg,Mn) (sub 3) (PO (sub 4) ) (sub 2) .4H (sub 2) O ; green; in small tabular crystals at Truro, Cornwall, U.K. Syn: lehrnerite.

ludwigite
 * An orthorhombic mineral, Mg (sub 2) FeBO (sub 5) ; forms a series with vosenite; forms finely fibrous masses. Includes magnesioludwigite, ferroludwigite. Syn: collbranite.

lue
 * Prov. Eng. To sift; a miner's term.

lueneburgite
 * Alternate spelling of lueneburgite.

lueshite
 * A monoclinic mineral, NaNbO (sub 3) ; perovskite group; pseudocubic; dimorphous with natroniobite. Syn: igdloite.

luffing cableway mast
 * A cableway tower hinged at the base and sustained by adjustable guys so that its inclination can be varied.

lug
 * a. A replaceable cutting member on an expansion reamer.

b. One of a set of cutting lugs used to cut off a length of casing in a borehole at any desired point below the collar of the hole. Syn: jaw.

lug down
 * To slow down an engine by increasing its load beyond its capacity.

lugeon test
 * Single-hole in situ test of formation permeability performed by measuring the volume of water taken in a section of test hole when the interval is pressurized at 10 bars (150 psi). Used primarily in variably permeable formations under evaluation for grouting.

Luhrig vanner
 * Vanning machine with side feed and end shake--a hybrid between the true vanner and the shaking table.

lumachelle
 * a. A compact, dark-gray or dark-brown limestone or marble, composed chiefly of fossil mollusk shells, and characterized by a brilliant iridescence or chatoyant reflection from within. Syn: fire marble.

b. Any accumulation of shells (esp. oysters) in stratified rocks. Etymol: French, coquina, oyster bed, from Italian lumachella, little snail.

lumber
 * Timber that has been sawed into boards, planks, staves, or other pieces of comparatively small dimensions. In mines, timber is used in the construction of coal chutes, mine cars, mine doors, forms for concrete structures, surface buildings, and for many other purposes.

lumber scale
 * A graduated measuring scale for determining the number of board feet in rough-sawed lumber.

luminance
 * A measure of surface brightness that is expressed as luminous flux per unit solid angle per unit projected area.

luminance of a surface
 * Luminous intensity per unit of apparent area; i.e., the area as projected on a plane normal to the direction of viewing. It is determined by the incident light flux falling upon the surface, the reflection factor of the surface, and the angle that the surface makes with the direction in which it is viewed. It is independent of distance; i.e., a surface appears equally bright no matter what the distance from which it is seen.

luminescence
 * a. The emission of light by a substance that has received energy or electromagnetic radiation of a different wavelength from an external stimulus; also, the light so produced. It occurs at temperatures lower than those required for incandescence. See also: phosphorescence; fluorescence.

b. Quantized electromagnetic emissions resulting from electrons in a crystal structure dropping from a higher excited state to a lower one. CF: thermoluminescence; triboluminescence.

luminosity
 * a. The quality of emitting or of giving out light; shining.

b. Subjective brightness sensation.

luminous
 * Radiating or emitting light; bright; clear.

Lumnite
 * Well-known brand of quicksetting cement for sealing rock cavities, plugging drill holes, etc. Is made from bauxite ore and limestone and is highly resistant to acids and heat.

lump coal
 * Bituminous coal in the large lumps remaining after a single screening that is often designated by the size of the mesh over which it passes and by which the minimum size lump is determined. Also, the largest marketable size.

Lump Coal
 * Trademark for permissible dynamites (types C and CC) with very low velocity of detonation. Are used in coal mining where maximum production of large-size coal is desired.

lump ore
 * See: natural ore.

lumpy
 * Describes a gemstone cut with too great a depth in proportion to its width.

lunar crater
 * See: crater.

lunker
 * Scot. A lenticular mass of sandstone or clay ironstone; a big nodule. CF: lonkey.

Lurgi process
 * This process consists of roasting iron ore in a reducing atmosphere, thus forming magnetic oxide of iron that is separated by crushing followed by magnetic separation. The internal structure of the kiln is so designed that the ore falls in a continuous veil through the current of reducing gases. Burners are distributed throughout the periphery of the kiln, so that roasting and reduction can be controlled in the various zones to the required temperature. Blast furnace gas for reduction passes into the center of the lower end of the kiln, while the gas and air for heating pass in from the circumference of the drum, nearer to the center and upper end of the furnace. The ingoing ore is crushed to give a maximum size of 20 mm, while the outgoing concentrate is crushed to 3.8 mm after cooling.

Lurmann front
 * An arrangement of water-cooled castings through which iron and cinder are tapped from the blast furnace, thus avoiding the use of a forehearth. See also: dam.

lurry
 * a. York. A weighted tram to which an endless rope is attached, fixed at the inby end of the plane, forming part of an appliance for taking up the slack rope.

b. A movable platform on wheels, the top of which is level with the bank or surface. It is run over the mouth of a shaft to receive the bucket when it reaches the top. A variation of lorry.

lusakite
 * A cobaltoan variety of staurolite.

lussatite
 * A fibrous variety of silica, possibly tridymite.

luster
 * the means for distinguishing them. There are several kinds of luster: metallic, the luster of metals; adamantine, the luster of diamonds; vitreous, the luster of broken glass; resinous, the luster of yellow resin, as that of eleolite; pearlylike pearl; and silkylike silk. These lusters have different degrees of intensity, being either splendent, shining, glistening, or glimmering. When there is a total absence of luster, the mineral is characterized as being dull.

b. In ceramics, a glaze, varnish, or enamel applied to porcelain in a thin layer, and giving it a smooth, glistening surface.

luster mottling
 * a. The macroscopic appearance of poikilitic rocks.

b. The shimmering appearance of a broken surface of a sandstone cemented with calcite, produced by the reflection of light from the cleavage faces of conspicuously large and independently oriented calcite crystals, 1 cm or more in diameter, incorporating colonies of detrital sand grains. It may also develop locally in barite, gypsum, or dolomite cements.

lutaceous
 * Said of a sedimentary rock formed from mud (clay- and/or silt-size particles) or having the fine texture of impalpable powder or rock flour; pertaining to a lutite. Also said of the texture of such a rock. CF: argillaceous; pelitic.

lutecite
 * A fibrous variety of chalcedony with fiber elongation perpendicular to the c crystallographic axis (opposite to normal chalcedony) and showing other optical anomalies.

luthos lazuli
 * A violet variety of fluorite.

luting
 * Sealing the joint of a retort with fire clay.

lutite
 * A general name used for consolidated rocks composed of silt and/or clay and of the associated materials which, when mixed with water, form mud; e.g., shale, mudstone, and calcilutite. The term is equivalent to the Greek-derived term "pelite." Etymol: Latin lutum, mud. Also spelled lutyte. See also: rudite; arenite.

lutose
 * Covered with clay; miry.

luxullianite
 * A granite characterized by phenocrysts of potassium feldspar and quartz that enclose clusters of radially arranged acicular tourmaline crystals in a groundmass of quartz, tourmaline, alkali feldspar, brown mica, and cassiterite. Its name is derived from Luxulyan, Cornwall. Also spelled: luxulianite; luxulyanite. Var: luxuliane.

luzonite
 * A tetragonal mineral, Cu (sub 3) AsS (sub 4) ; stannite group; dimorphous with enargite. Formerly considered an arsenian variety of famatinite.

lyddite
 * High explosive based on picric acid, (NO (sub 2) ) (sub 3) C (sub 6) H (sub 2) OH, with 10% nitrobenzene and 3% vaseline.

Lydian stone
 * A touchstone consisting of a compact, extremely fine-grained, velvet- or gray-black variety of jasper. Etymol: Greek Lydia, ancient country in Asia Minor. Syn: lydite; touchstone; basanite.

lydite
 * See: Lydian stone. Also spelled: lyddite.

lye
 * See: double parting.

lying money
 * An allowance to miners on piecework who are rendered idle during a shift owing to circumstances beyond their control, such as a breakdown in power services, or supplies of empty cars.

lying wall
 * See: footwall.

lynx eye
 * Green iridescent labradorite.

lynx sapphire
 * a. Dark blue iolite variety of cordierite.

b. Dark blue sapphires in Sri Lanka.

lyophilic
 * a. Condition of solid-liquid mixture in which surface-active molecules that contain two or more groups have both an affinity for the phase in which one group is dissolved, and a repulsion from this phase for another group or ion. See also: hydrophilic.

b. Having the property of attracting liquids.

lyophobic
 * Of, relating to, or having a lack of strong affinity between a dispersed phase and the liquid in which it is dispersed; systems such as colloidal metals in water are easily coagulated. Opposite of lyophilic.

lyosorption
 * Adsorption of liquid to a solid surface.

lype
 * Scot. An irregularity in the mine roof. A projecting rock in a mine roof that may fall at any time. Usually used in the plural, and sometimes spelled lipe.

Lyster process
 * A flotation process that separates galena and zinc blende by treatment, at a low temperature, with eucalyptus oil or other frothing agent, and with agitation or aeration in a neutral or alkaline, but not acid, solution of the sulfates, chlorides, or nitrates of calcium, magnesium, sodium, potassium, or mixtures of these substances.

lyway
 * This term is commonly used in and around mines in Indiana and Illinois to describe a mine sidetrack or a passing track.