Appendix:Dictionary of Mining, Mineral, and Related Terms/L/3

lindackerite
 * A monoclinic mineral, H (sub 2) Cu (sub 5) (AsO (sub 4) ) (sub 4) .8-9H (sub 2) O ; green; forms rosettes and reniform masses with one perfect cleavage.

Lindblad-Malmquist gravimeter
 * See: Boliden gravimeter.

lindgrenite
 * A monoclinic mineral, Cu (sub 3) (MoO (sub 4) ) (sub 2) (OH) (sub 2) ; green; in tabular crystals from Chuquicamata, Chile.

Lindgren's volume law
 * See: law of equal volumes.

lindstroemite
 * An orthorhombic mineral, Pb (sub 3) Cu (sub 3) Bi (sub 7) S (sub 15) . Also spelled lindstroemite.

line
 * a. The limit of a surface; a length without breadth; an outline; a contour.

b. The course in which anything proceeds, or which anyone takes; direction given or assured. c. A cable, rope, chain, or other flexible device for transmitting pull. d. To line pieces up in order to couple them together. e. See: plumbline.

lineage
 * An imperfection in a crystal structure characterized by a series of line defects, but not extensive enough to form a grain boundary. CF: grain boundary; crystal defect.

lineal foot
 * A foot in length as distinguished from square foot or cubic foot.

lineal travel
 * Commonly used as a syn. for peripheral speed, as applied to bit rotation; also, a syn. for rope or cable speed, as applied to hoisting.

lineament
 * a. A significant line of landscape that reveals the hidden architecture of the rock basement. Lineaments are character lines of the Earth's physiognomy.

b. A topographic feature; esp., one that is rectilinear. c. A topographic line that is structurally controlled. Lineaments are studied esp. on aerial photographs. Sometimes inappropriately called a linear.

linear
 * Arranged in a line or lines; pertaining to the linelike character of some object or objects.--n. Not recommended as a syn. of lineament.

linear alkylbenzene sulfonate
 * A high-quality, biodegradable detergent, obtained from lignite tar, which is derived from carbonizing coal at low temperatures.

linear element
 * A fabric element having one dimension that is much greater than the other two. Lineations are the common linear elements. CF: planar element; equant element.

linear expansion
 * The increase in one dimension of a soil mass, expressed as a percentage of that dimension at the shrinkage limit to any given water content.

linear model
 * A function frequently used when fitting mathematical models to experimental variograms, often in combination with a nugget model.

linear parallelism
 * See: lineation.

linear schistosity
 * A schistosity due to the parallel alignment of columnar or acicular crystals in rocks.

linear shrinkage
 * Decrease in one dimension of a soil mass, expressed as a percentage of the original dimension, when the water content is reduced from a given value to the shrinkage limit.

linear structure
 * See: lineation.

lineation
 * A general, nongeneric term for any linear structure in a rock; e.g., flow lines, slickensides, linear arrangements of components in sediments, or axes of folds. Lineation in metamorphic rocks includes mineral streaking and stretching in the direction of transport, crinkles and minute folds parallel to fold axes, and lines of intersection between bedding and cleavage, or of variously oriented cleavages. Syn: linear structure; linear parallelism.

line brattice
 * A partition placed in an opening to divide it into intake and return airways. See also: brattice.

line clinometer
 * A borehole-survey clinometer designed to be inserted between rods at any point in a string of drill rods. CF: clinometer; end clinometer; plain clinometer; wedge clinometer.

line defect
 * An imperfection in crystal structure characterized by an atomic layer extending part way into a crystal structure. CF: crystal defect; edge dislocation.

line drilling
 * A term used in quarrying to describe the method of drilling and broaching for the primary cut. In this method, deep holes are drilled close together in a straight line by means of a reciprocating drill mounted on a bar. The webs between the holes are removed with a drill or a flat broaching tool; thus a narrow continuous channel cut is made. See also: broaching; controlled blasting.

line drop
 * Loss in voltage owing to the resistance of conductors conveying electricity from a power station to the consumer.

line electrode
 * A series of electrodes put out along a straight line on the surface and electrically interconnected, approx. the condition of continuous electrical contact with the Earth along that line.

line lubricator
 * See: line oiler.

line map
 * See: planimetric map.

line of bearing
 * a. The compass direction of the course a borehole follows.

b. A syn. for strike as applied to a rock stratum. c. The direction of the strike. See: strike.

line of collimation
 * The line of sight of the telescope of a surveying instrument, defined as the line through the rear nodal point of the objective lens of the telescope and the center of the reticle when they are in perfect alignment. See also: line of sight.

line of creep
 * The path that water follows along the impervious surface of contact between the foundation soil and the base of a dam or other structure. Syn: path of percolation.

line of dip
 * a. The direction in which an inclined borehole is pointed.

b. The line of greatest inclination of a stratum from the horizontal plane. c. The direction of the angle of dip, measured in degrees by compass direction. It generally refers to true dip, but can be said of apparent dip as well. Syn: direction of dip.

line of force
 * a. The straight line in which a force acts.

b. A curve in a field of force drawn so that at every point it has the direction of resultant force; specif., a line of magnetic force.

line of least resistance
 * The shortest distance between the center line of a drill hole and the free rock face.

line of outcrop
 * The intersection of a stratum with the ground surface.

line of seepage
 * The upper free-water surface of the zone of seepage. Syn: seepage line; phreatic line.

line of sight
 * The sighting or pointing line of a telescope, defined by the optical center of the objective and the intersection of crosshairs. See also: line of collimation.

line of thrust
 * Locus of the points through which the resultant forces in an arch or retaining wall pass.

line of tunnel
 * The width marked by the exterior lines or sides of a tunnel.

line oiler
 * An apparatus inserted in a line conducting air or steam to an air- or steam-actuated machine that feeds small controllable amounts of lubricating oil into the air or steam. Also called lubricator; potato. Syn: air-line lubricator; line lubricator; oil pot; oiler; pineapple; pot. See also: atomizer.

liner
 * a. A foot piece for uprights in timber sets.

b. Timber supports erected to reinforce existing sets that are beginning to collapse due to heavy strata pressure. c. A string of casing in a borehole. d. See: lining.

lines
 * Plumblines, not less than two in number, hung from hooks driven in wooden plugs. A line drawn through the center of the two strings or wires, as the case may be, represents the bearing or course to be driven on.

linesman
 * An assistant to a surveyor.

lines up
 * The number of lines strung through the traveling block and crown block.

line timbers
 * Timbers placed along the sides of the track of a working place in rows on some predetermined plan.

line up
 * a. A command signifying that the drill runner wants the hoisting cable attached to the drill stem, threaded through the sheave wheel, or wound on the hoist drum.

b. To reposition a drill so that the drill stem is centered over and parallel to a newly collared drill hole. c. Regular linear pattern of peaks or troughs on a seismogram, such as occurs when a reflection comes in.

lingot
 * An iron ingot mold.

lining
 * a. A casing of brick, concrete, cast iron, or steel, placed in a tunnel or shaft to provide support. See also: tunnel lining.

b. In grinding of rocks and ores, a layer of wear-resistant material, used to protect rock breakers, shells of ball mills, chutes, launders, and other areas subject to abrasion. Special plastics, rubber, and acid-resistant alloys are used in vats, piping, and autoclaves, and for pump impellers exposed to abrasion and chemical attack. See also: scour protection. c. A cover of clay, concrete, synthetic film, or other material, placed over all or part of the perimeter of a conduit or reservoir, to resist erosion, minimize seepage losses, withstand pressure, and improve flow. d. Supporting the rock sides of a mine gallery is known as lining, and the material used in so doing is called the lining. e. The planks arranged against frame sets. f. Refractory brickwork of furnace used to protect hearth, bosh, roof, or walls. g. The brick, concrete, cast iron, or steel casing placed around a tunnel or shaft as a support. Timber sets are not viewed as a lining. See also: brick walling; guniting; liner; permanent shaft support.

lining mark
 * Eng. A drill hole in the mine roof with a wooden plug driven into it from which to hang a plumbline.

lining sight
 * An instrument consisting essentially of a plate with a longitudinal slot in the middle, and the means of suspending it vertically. It is used in conjunction with a plumbline for directing the courses of underground drifts, headings, etc.

lining up a mine
 * In surveying, placing the sights for driving entries, drifts, or rooms nearer the working face.

linishing
 * The operation of polishing as carried out on a linisher. This machine is designed for the polishing of flat objects and carries a flat revolving cloth belt whose surface is impregnated with a suitable abrasive material.

link bar
 * A lightweight steel bar extending faceward from the steel supports behind the conveyor. It supports the area between the conveyor and the coal on longwall faces where cutter loaders are carried on armored flexible conveyors. The joint and locking device may consist of a hinge pin and wedge. The standard bar can carry in cantilever a maximum tip load of about 2 st (1.8 t). In general, linked bars are stronger than corrugated straps and wooden bars, and their use is increasing.

link conveyor
 * A chain conveyor.

linked veins
 * An ore-deposit pattern in which adjacent, more or less parallel veins are connected by diagonal veins or veinlets.

Linkenbach table
 * In mineral processing, a stationary round table onto which finely divided pulp (slimes) is fed from the center from a revolving feed box. A light wash of water follows, and lighter particles are washed downslope to a peripheral discharge launder. Behind this a heavier water flush displaces the settled heavier material (concentrates) and flushes it down to a bridging arrangement that delivers it to a separate discharge.

link-plate belt
 * A grizzly type of belt consisting of two strands of endless chain connected by through rods at each articulation, on which are carried a series of plates or bars mounted in a vertical plane for the purpose of rough screening while conveying. Syn: belt.

linnaeite
 * a. An isometric mineral, 8[Co (sub 3) S (sub 4) ] ; commonly has small amounts of Ni, Fe, Cu; forms a series with polydymite; crystallizes in octahedra with cubic cleavage; metallic; steel gray tarnishing to copper red; in quartz sulfide veins; a source of cobalt. Also spelled linneite.

b. The mineral group bornhardtite, carrollite, daubreelite, fletcherite, greigite, indite, linnaeite, polydymite, siegenite, truestedite, tyrrellite, and violarite.

linneite
 * Alternate spelling of linnaeite.

linoleic acid
 * An unsaturated fatty acid, CH (sub 3) (CH (sub 2) ) (sub 4) CH = CH(CH (sub 2) ) (sub 7) COOH, used as a collector in the flotation process.

linolenic acid
 * An unsaturated fatty acid, CH (sub 3) CH (sub 2) CH = CH CH (sub 2) CH = CH CH (sub 2) CH = CH(CH (sub 2) ) (sub 7) COOH.

linophyric
 * Pertaining to porphyritic rocks in which the phenocrysts are arranged in lines or streaks.

linseed fatty acid
 * Byproduct of manufacture of linseed oil. Flotation agent used as collector, emulsifier, or stabilizer for davidite, a uranium mineral.

linsey
 * Lanc. A strong, striped shale and a streaky, banded sandstone or siltstone, interbedded in such a manner as to resemble a mixed linen and woolen fabric (linsey-woolsey). CF: whintin.

lintel
 * A horizontal supporting member spanning a wall opening.

Linz-Donawitz process
 * A process for making steel from cast iron; it resembles the Bessemer process except for two important differences: (1) oxygen is used rather than air and (2) instead of blowing the gas through tuyeres submerged in the bath (as in the Bessemer converter), the oxygen stream impinges on the surface of the molten iron.

lionite
 * See: tellurium.

lip
 * a. The digging edge of a dredge bucket.

b. The cutting edge of a fixed-wing bit, such as the cutting edge on a fishtail bit.

lip-and-gate builder
 * One who constructs lips and gates that support and regulate flow of molten glass from furnace to glass-rolling machine.

liparite
 * A syn. of rhyolite used by German and Soviet authors. Its name, given by Roth in 1861, is derived from the Lipari Islands, in the Tyrrhenian Sea. Not recommended usage; the much more widely used syn. rhyolite has priority by 1 yr.

lip of shaft
 * Eng. The bottom edge of a shaft circle where it is open to the seam workings.

lip screen
 * a. A common term applied to stationary screens installed in the loading chutes over which the coal flows as it is loaded into railroad cars for market.

b. A small screen or screen bars, placed at the draw hole of a coal pocket to take out the fine coal.

liptinite
 * See: exinite.

liptite
 * Term used to describe a microlithotype consisting mainly of the exinite group of macerals and esp. of sporinite. Contains not less than 95% of exinite (liptinite) with thickness (bands) of exinite greater than 50 mu m recorded as liptite (sporite). Liptite (sporite) is a rare constituent of hard coal. CF: vitrite.

Liqnipel process
 * A process for reducing high-moisture-content lignite from up to 40% moisture to about 10% moisture by pulverizing the raw coal, pelletizing the 14-mesh top size, thermally drying, and then mixing with a binder. The final product exhibits good handling and storage properties, and resists spontaneous combustion.

liquation
 * a. A method of recovering sulfur by liquefying it under pressure and heat, drawing off the molten sulfur, and allowing it to solidify.

b. The heating of a solid mixture until one of the constituents melts and can be separated from the solid remaining.

liquid air
 * Air in the liquid state but usually richer in oxygen than gaseous air. A faintly bluish, transparent, mobile, intensely cold liquid. Obtained by compressing purified air and cooling it by its own expansion to a temperature below the boiling points of its principal components, nitrogen (-195.8 degrees C, at 760 mm) and oxygen (-182.96 degrees C, at 760 mm). Used chiefly as a refrigerant and as a source of oxygen, nitrogen, and inert gases (as argon).

liquidation grade
 * The amount paid by the smelter or other purchaser per ton of ore mined.

liquid bituminous material
 * Material having a penetration at 77 degrees F (25 degrees C), under a load of 50 g applied for 1 s, of more than 350.

liquid glass
 * See: water glass.

liquid inclusion
 * A partial syn. of fluid inclusion.

liquid-liquid extraction
 * See: solvent extraction.

liquid measure
 * Includes the following: 4 gills (gi) equal 1 pint (pt) or 0.47 L; 2 pt equal 1 quart (qt) or 0.95 L; 4 qt equal 1 gal or 3.785 L; 31-1/2 gal equal 1 bbl or 119.2 L; and 2 bbl equal 1 hogshead (hhd) or 238.5 L.

liquid-phase sintering
 * Sintering of a compact or loose powder aggregate under conditions where a liquid phase is present during part of the sintering cycle.

liquid pressure
 * The pressure of a liquid on the surface of its container or on the surface of any body in the liquid is equal to the weight of a column of the liquid whose height equals the depth of the liquid at that certain point.

liquids flowsheet
 * A flowsheet to indicate the flow of liquids throughout a series of operations.

liroconite
 * A monoclinic mineral, Cu (sub 2) Al(AsO (sub 4) )(OH) (sub 4) .4H (sub 2) O ; soft; blue to green; occurs with malachite in the oxidized zone of copper deposits. Syn: lentil ore.

liskeardite
 * A possibly orthorhombic mineral, (Al,Fe) (sub 3) (AsO (sub 4) )(OH) (sub 6) .5H (sub 2) O ; forms thin encrustations at Liskear, Cornwall, U.K.

list
 * a. Mid. Dull coal, sometimes dirty.

b. Derb. and Leic. A hard parting between coal seams. c. York. A weak shale or a thin bed of any kind of rock. d. Eng. A mine inspector's term for the schedule of particulars of accidents.

listing
 * a. Fine shale or clay with glossy surfaces or slickensides due to crushing and relative movement. The rock may form a layer over a coal seam as clod; also applied to leather bed.

b. See: lashing.

list mill
 * In gem cutting, a wheel covered with list or cloth on which gems are polished. Also called list wheel.

list pan
 * A perforated skimmer for skimming molten tin.

listric fault
 * A curved downward-flattening fault, generally concave upward. Listric faults may be characterized by normal or reverse separation.

listy bed
 * Soft freestone between the Chert Vein and House Cap in the Portland beds at Winspit, Purbeck, U.K.

lith-
 * A prefix meaning stone or stonelike.

litharge
 * A tetragonal mineral, PbO ; red; dimorphous with massicot, which is yellow. Syn: lead ocher; lithargite.

lithargite
 * See: litharge.

lithia amethyst
 * See: kunzite; spodumene.

lithia emerald
 * See: hiddenite; spodumene.

lithia mica
 * See: lepidolite.

lithic
 * a. A syn. of lithologic, as in lithic unit.

b. Said of a medium-grained sedimentary rock, and of a pyroclastic deposit, containing abundant fragments of previously formed rocks; also said of such fragments. c. Pertaining to or made of stone; e.g., lithic artifacts or lithic architecture.

lithic arenite
 * a. A sandstone containing abundant quartz, chert, and quartzite, less than 10% argillaceous matrix, and more than 10% feldspar, and characterized by an abundance of unstable materials in which the fine-grained rock fragments exceed feldspar grains. The rock is roughly equivalent to subgraywacke.

b. See: lithic sandstone.

lithic graywacke
 * A graywacke characterized by abundant unstable materials; specif. a sandstone containing a variable amount (generally less than 75%) of quartz and chert and 15% to 75% detrital-clay matrix, and having rock fragments (primarily of sedimentary or low-rank metamorphic origin) in greater abundance than feldspar grains (chiefly sodic plagioclase, indicating a plutonic provenance).

lithic sandstone
 * A sandstone containing rock fragments in greater abundance than feldspar grains. Syn: lithic arenite.

lithic tuff
 * An indurated deposit of volcanic ash in which the fragments are composed of previously formed rocks; e.g., accidental particles of sedimentary rock, accessory pieces of earlier lavas in the same cone, or small bits of new lava (essential ejecta) that first solidify in the vent and are then blown out. CF: crystal tuff.

lithidionite
 * Alternate spelling of litidionite. See: litidionite.

lithifaction
 * See: lithification.

lithification
 * a. A compositional change in a coal seam from coal to bituminous shale or other rock; the lateral termination of a coal seam due to a gradual increase in impurities.

b. The conversion of a newly deposited, unconsolidated sediment into a coherent, solid rock, involving processes such as cementation, compaction, desiccation, and crystallization. It may occur concurrent with, soon after, or long after deposition. c. A term sometimes applied to the solidification of a molten lava to form an igneous rock. See also: consolidation; induration. Syn: lithifaction.

lithionite
 * See: lepidolite.

lithiophilite
 * An orthorhombic mineral, 4[LiMnPO (sub 4) ] ; forms a series with triphylite; in granite pegmatites; an ore of lithium.

lithiophorite
 * A hexagonal or monoclinic mineral, (Al,Li)MnO (sub 2) (OH) (sub 2) ; powdery; black; occurs with other supergene manganese oxide minerals.

lithiophosphate
 * An orthorhombic mineral, Li (sub 3) PO (sub 4) ; in white to colorless masses in pegmatite; Kola Peninsula, Russia.

lithium
 * A soft, silvery-white metallic element of the alkali group, the lightest of all metals. Symbol, Li. Does not occur free in nature; is found combined in small amounts in nearly all igneous rocks and in the waters of many mineral springs. Lepidolite, spodumene, petalite, and amblygonite are the more important minerals containing it. The metal is corrosive and requires special handling. Used as an alloying agent, in the synthesis of organic compounds, and for nuclear applications.

lithium borosilicate
 * LiBSiO (sub 4) . Used in low-temperature enamels and as a component of high-temperature, corrosion-resistant coatings.

lithium mica
 * See: lepidolite.

lithium niobate
 * LiNbO (sub 3) ; a ferroelectric compound having the ilmenite structure and of potential interest as an electroceramic.

lithium tantalate
 * LiTaO (sub 3) ; a ferroelectric compound of potential value as a special electroceramic. The Curie temperature is above 350 degrees C.

lithodeme
 * A body of intrusive, pervasively deformed, or highly metamorphosed rock, generally nontabular and lacking primary depositional structures, and characterized by lithic homogeneity. It is mappable at the surface and traceable in the subsurface. For cartographic and hierarchical purposes, it is comparable to a formation. The name of a lithodeme combines a geographic term with a lithic or descriptive term, e.g., Duluth Gabbro. CF: suite. Adj: lithodemic.

lithofacies
 * The rock record of any sedimentary environment, including both physical and organic characters. It is a mappable subdivision of a designated stratigraphic unit, distinguished from adjacent subdivisions on the basis of lithology. See also: facies.

lithofracteur
 * Nitroglycerine mixed with siliceous earth, charcoal, sodium, and sometimes barium, nitrate, and sulfur.

lithogene
 * Said of a mineral deposit formed by the process of mobilization of elements from a solid rock and their transportation and redeposition elsewhere. On a local scale, the process may be called a product of lateral secretion; on a larger scale, the deposit may be called a product of regional metamorphism.

lithogenesis
 * The origin and formation of rocks, esp. of sedimentary rocks. Also, the science of the formation of rocks. CF: petrogenesis. Syn: lithogeny. Adj: lithogenetic.

lithogenesy
 * The science of the origin of minerals and the causes of their modes of occurrence.

lithogenetic
 * Of or pertaining to the origin or formation of rocks.

lithogeny
 * See: lithogenesis.

lithoglyph
 * A carving or engraving on a stone or gem; also, a stone or gem so engraved.

lithoglyptics
 * The art of gem cutting; the cutting or engraving of precious stones or gems.

lithographic limestone
 * A compact, dense, homogeneous, exceedingly fine-grained limestone having a pale creamy yellow or grayish color and a conchoidal or subconchoidal fracture. It was formerly much used in lithography for engraving and the reproduction of colored plates. See also: Solenhofen stone. Syn: lithographic stone.

lithographic stone
 * See: lithographic limestone.

lithographic texture
 * A sedimentary texture of certain calcareous rocks, characterized by uniform particles of clay size and by an extremely smooth appearance resembling that of the stone used in lithography.

lithoid
 * Rocklike or stonelike.

lithoidal
 * Said of the texture of some dense, microcrystalline igneous rocks, or of devitrified glass, in which individual constituents are too small to be distinguished with the unaided eye.

lithologic
 * Adj. of lithology. Syn: lithic.

lithologic correlation
 * The matching or linking up of identical rock formations, veins, or coal seams, exposed some distance apart, by lithology. See also: correlation.

lithology
 * a. The character of a rock described in terms of its structure, color, mineral composition, grain size, and arrangement of its component parts; all those visible features that in the aggregate impart individuality to the rock. Lithology is the basis of correlation in coal mines and commonly is reliable over a distance of a few miles.

b. The study of rocks based on the megascopic observation of hand specimens. In French usage, the term is synonymous with petrography.

lithomarge
 * A smooth, indurated variety of common kaolin, consisting at least in part of a mixture of kaolinite and halloysite.

lithophile
 * a. Said of an element that is concentrated in the silicate rather than in the metal or sulfide phases of meteorites. Such elements concentrate in the Earth's silicate crust in Goldschmidt's tripartite division of elements in the solid Earth. CF: chalcophile; siderophile.

b. Said of an element with a greater free energy of oxidation per gram of oxygen than iron. It occurs as an oxide and more often as an oxysalt, esp. in silicate minerals. Examples are Se, Al, B, La, Ce, Na, K, Rb, Ca, Mn, U. Syn: oxyphile.

lithophosphor
 * A mineral, such as barite, that becomes phosphorescent when heated. Syn: lithophosphore.

lithophosphore
 * See: lithophosphor.

lithophysae
 * Hollow, bubblelike, or roselike spherulites, usually with a concentric structure, that occur in rhyolite, obsidian, and related rocks. Sing: lithophysa.

lithopone
 * A white pigment composed of a mixture of barium sulfate, zinc sulfide, and zinc oxide.

lithospar
 * A naturally occurring mixture of spodumene and feldspar.

lithosphere
 * a. The solid outer portion of the Earth, as compared with the atmosphere and the hydrosphere.

b. In plate tectonics, an outer layer of great strength relative to the underlying asthenosphere for deformation at geologic rates. It includes the crust and part of the upper mantle and is about 100 km thick.

lithotope
 * An area or surface of uniform sediment, sedimentation, or sedimentary environment, including associated organisms. CF: lithofacies.

lithotype
 * a. A rock defined on the basis of certain selected physical characters. b. This term was proposed by C.A. Seyler in 1954 in a communication to the Nomenclature Subcommittee of the International Committee for Coal Petrology to designate the different macroscopically recognizable bands of humic coals. These bands were described by M.C. Stopes in 1919 as the four visible ingredients in banded bituminous coal. The following macroscopic bands are distinguished in humic coals: vitrain, clarain, durain, and fusain.

lithoxyl
 * Wood opal in which the original woody structure is observable; also petrified (opalized) wood. Also spelled lithoxyle; lithoxylite; lithoxylon. See also: wood opal.

litidionite
 * Blue triclinic mineral, KNaCuSi (sub 4) O (sub 10).

litmus
 * A blue dyestuff that turns red when treated by an acid and remains blue when treated by an alkali.

litmus paper
 * Absorbent paper dipped into a solution of litmus. Used to test solutions to determine whether they are acid or alkaline.

lit-par-lit
 * Having the characteristic of a layered rock, the laminae of which have been penetrated by numerous thin, roughly parallel sheets of igneous material, usually granitic. Etymol: French, bed-by-bed. CF: injection gneiss; injection metamorphism.

Little Demon exploder
 * Trade name for a small exploder that employs a manually operated electromagnetic generator as its source of power. It is approved for firing single shots in gassy mines and is in widespread use. Syn: one-shot exploder.

little giant
 * A jointed iron nozzle used in hydraulic mining. See also: hydraulic monitor.

little winds
 * a. Corn. A sump.

b. An underground shaft, sunk from a horizontal drift. A winze.

littoral
 * Of or pertaining to a shore. A coastal region.

littoral current
 * A current generated by waves breaking at an angle to the shoreline and that usually moves parallel to and adjacent to the shoreline within the surf zone. See also: longshore current.

littoral drift
 * a. Applied to the movement along the coast of gravel, sand, and other material composing the bars and beaches.

b. Material moved in the littoral zone under the influence of waves and currents.

littoral zone
 * In mine subsidence, the zone that embraces the disturbed strata lying round about and outside the mined strata.

live boom
 * A shovel boom that can be lifted and lowered without interrupting the digging cycle.

liveingite
 * A monoclinic mineral, Pb (sub 9) As (sub 13) S (sub 28) . Syn: rathite-II.

live load
 * a. In drilling, a variable load suspended on the hoist line.

b. In mechanics, a load that is variable, as distinguished from a load that is constant. Also called dynamic load. c. A load on a structure that may be removed or its position altered. See also: dead load. d. It may not be a dynamic load, and it does not include wind load or earthquake shocks.

live lode
 * A lode containing valuable minerals.

liverite
 * Utah. A variety of bitumen, probably elaterite.

live roll grizzly
 * A device for screening and scalping that consists of a series of spaced rotating, parallel rolls so constructed as to provide openings of a fixed size. See also: grizzly.

liver opal
 * See: menilite.

liver ore
 * A miners' term for cinnabar.

liver pyrites
 * A massive form of iron sulfide (marcasite and sometimes also pyrite and pyrrhotite) having a dull liver-brown color.

liver rock
 * A sandstone that breaks or cuts as readily in one direction as in another and that can be worked without being affected by stratification; a dense freestone that lacks natural division planes.

liverstone
 * A variety of barite that gives off a fetid odor when rubbed or heated.

livesite
 * A clay mineral intermediate to kaolinite and halloysite; a disordered kaolinite.

live steam
 * Steam direct from the boiler and under full pressure. Distinguished from exhaust steam, which has been deprived of its available energy.

livingstonite
 * A monoclinic mineral, HgSb (sub 4) S (sub 8) ; metallic lead gray.

lixiviant
 * A liquid medium that selectively extracts the desired metal from the ore or material to be leached rapidly and completely, and from which the desired metal can then be recovered in a concentrated form.

lixiviation
 * See: leaching.

lixivium
 * See: leachate.

lizardite
 * A trigonal and hexagonal mineral, Mg (sub 3) Si (sub 2) O (sub 5) (OH) (sub 4) ; kaolinite-serpentine group; polymorphous with antigorite, clinochrysotile, orthochrysotile, and parachrysotile; forms a series with nepouite; in platy masses as an alteration product of ultramafic rocks; the most abundant serpentine mineral.

L-joint
 * An approx. horizontal joint plane in igneous rocks. Syn: primary flat joint.

llano
 * A term for an extensive tropical plain, with or without vegetation, applied esp. to the generally treeless plains of northern South America and the Southwestern United States. Etymol: Spanish.

load
 * a. See: bit load.

b. The act or process of placing an explosive in a borehole; also, the explosive so placed. See also: charge.

load-bearing test
 * Load-bearing tests may be divided into two types, horizontal and vertical. Both types require excavation of a test pit into the region that is being investigated. This test pit must be excavated with a minimum of blasting, with particular attention to the bearing surfaces to avoid disturbance of the foundation rock. Load-bearing tests are being used to an increasing extent as a source of information for the design of heavily loaded surface structures and have supplanted seismic tests where the foundation rock is highly shattered. Syn: horizontal load-bearing test.

load-bearing wall
 * A wall carrying any load put upon it together with its own weight and the wind load.

load binder
 * A lever that pulls two grabhooks together, and holds them by locking over center.

load cell
 * Consists essentially of a hollow steel cylinder capped top and bottom by a steel plate. Strain gages are cemented on the inner wall of the cylinder in such a way that, as the cylinder is compressed, the strain gages will be distorted, with a resultant change in resistance. This instrument is designed for measuring the load transferred from the hanging wall onto props or other units used for support.

load controller
 * A device to control the load and prevent spillage on a gathering conveyor receiving coal or mineral from several loading points or subsidiary conveyors. The device is a simplified weightometer and is installed on the main belt a short distance before the intermediate loading point. When the main belt is fully loaded, the scale registers this fact and causes a break in the electrical circuit of the intermediate conveyor, which is stopped. Immediately after that, the flood loading on the main conveyor is finished, and the load controller operates and starts up the subsidiary conveyor.

load dropper
 * See: car runner; car dropper.

loaded filter
 * A graded filter placed at the foot of an earth dam or other construction, stabilizing the foot of the structure by virtue of its weight and permeability.

loaded hole
 * A drilled borehole in which explosive materials are loaded without priming the hole or including an initiator.

loaded wheel
 * A grinding wheel that has a glazed or clogged surface from particles of the material being ground.

loader
 * a. A mechanical shovel or other machine for loading coal, ore, mineral, or rock. Syn: mechanical loader. See also: loading machine; scraper loader; shaker-shovel loader; shovel loader; cutter loader; gathering arm loader.

b. The worker who loads coal, either by hand or by operating a loading machine, at the working face after the coal has been shot down; also keeps the working place in order. Syn: loader operator. See also: hand loader. c. In anthracite and bituminous coal mining, a laborer who shovels coal or rock, blasted from the working face in a mine, into cars or onto a conveyor belt from which cars are loaded at some point removed from the working place. May be designated as car loader; conveyor loader. Also called coal loader. d. In metal and nonmetal mining, one who shovels ore or rock, caved or blasted from the working face in a mine, into cars or onto a conveyor belt from which cars are loaded at some point removed from the working place. e. See also: gun-perforator loader; tractor shovel. Syn: loader engineer; loader runner; loader operator..

loader boss
 * a. In bituminous coal mining, a foreperson who supervises a crew of loaders loading coal onto a conveyor or into cars at working places in a mine. Also called loading boss; loading-unit boss.

b. In anthracite coal mining, a foreperson who supervises the loading of railroad cars with prepared coal.

loader engineer
 * See: loader; boxcar loader.

loader gate
 * A gate road equipped with a gate conveyor or a gate-end loader; the gate to which the face conveyors deliver their coal.

loader-off
 * Eng. A man who regulates the sending out of the full cars from a longwall stall, or gate.

loader operator
 * See: loader.

loader runner
 * See: boxcar loader; loader.

load-extension curve
 * A line plotted from the results of a tensile test on metal, the loads being shown as ordinates and the elongations of the gage length as abscissae, thus relating the extension of the material under test to the applied load. See also: stress-strain curve.

load factor
 * a. The ratio of the average compressor load during a certain period of time to the maximum rated load of the compressor.

b. The ratio of the collapse load to the working load on a structure or section. c. In electric power engineering, the ratio of average electrical load to peak electrical load, usually calculated over a 1-h period. d. Average load carried by an engine, machine, or plant, expressed as a percentage of its maximum capacity. e. Ratio of average output during a period to maximum output during the period. Sometimes the ratio of output to maximum capacity.

load fold
 * A plication of an underlying stratum, believed to result from unequal pressure and settling of overlying material.

load indicator
 * A measuring device used to indicate the load or weight suspended on a drill hoisting line or cable.

loading
 * In ion exchange, sorption onto resins of metallic ions from a pregnant solution in loading cycle.

loading boom
 * a. In coal preparation, an overhanging steel chute for loading coal into rail wagons or lorries; usually capable of vertical movement as loading proceeds to minimize breakage.

b. An adjustable conveyor used for lowering coal into cars with little breakage. Widely used for handling domestic sizes of bituminous coal. c. A hinged portion of a conveyor that is designed to receive materials at a fixed level and to discharge them at varying levels; usually employed for loading coal into wagons.

loading-boom operator
 * See: conveyor man.

loading boss
 * See: loader boss.

loading chute
 * a. A three-sided tray for loading or for transfer of material from one transport unit to another. See also: chute.

b. A gravity chute used to convey coal from the pocket or the screen to the railroad car. c. Used to direct material onto a conveyor.

loading conveyor
 * Any of several types of conveyors adapted for loading bulk materials, packages, or objects into cars, trucks, or other conveyors. See also: portable conveyor.

loading density
 * The number of pounds of explosive per foot length of drill hole.

loading equipment
 * Mechanical shovels or other machines singly or in combination used to load excavated or stockpiled materials into trucks, mine cars, conveyors, or other transportation or haulage units.

loading head
 * That part of a loading machine that gathers the coal or rock and places it on the machine's elevating conveyor.

loading-head man
 * One who operates the loading device of any type of conveyance equipped with a self-loading head for the mechanical underground loading of coal or other mineral.

loading hopper
 * A hopper used to receive and direct material to a conveyor.

loading machine
 * a. A generic term for any power-operated machine for loading mined coal or any other material into mine cars, conveyors, road vehicles, or bins.

b. A machine for loading materials, such as coal, ore, or rock, into cars or other means of conveyance for transportation to the surface of the mine. See also: loader.

loading machine operator
 * A person who operates a mobile loading machine. Syn: loading-machine runner.

loading-machine runner
 * See: loading machine operator.

loading pan
 * A box or scoop into which broken rock is shoveled in a sinking shaft while the hoppit is traveling in the shaft. A small hoist is used to lift and discharge the pans into the hoppit on its return to the shaft bottom. See also: box filling.

loading pick
 * Eng. A pick for cleaning coal.

loading point
 * a. The point where coal or ore is loaded into cars or conveyors, where a conveyor discharges into mine cars, or where a wagon or lorry is loaded. See also: transfer point.

b. N. of Eng. Where coal is transferred from a mother gate or trunk belt conveyor into tubs.

loading pole
 * A nonmetallic pole used to assist the placing and compacting of explosive charges in boreholes.

loading ramp
 * A surface structure, often incorporating storage bins, used for gravity loading bulk material into transport vehicles.

loading ratio
 * In quarrying, the number of tons of rock blasted per 1 lb (0.454 kg) of explosive. The harder the rock, the lower the ratio. See also: explosive factor; explosive ratio. Also called powder factor.

loadings
 * Eng. Pillars of masonry carrying a winding drum or pulley.

loading shovel
 * A mechanical shovel able to operate as a forklift truck, a crane, or a loader. See also: shovel loader.

loading station
 * A device consisting of one or more plates, or a hopper receiving and placing material on the conveyor belt for transport. When such a loading station is located at the tail end, it is known as a tail-end loading station; when it is located along the intermediate section, it is known as an intermediate loading station.

loading-unit boss
 * See: loader boss.

loading weight
 * Weight of a powder that is filled into a container under stated conditions. See also: bulk density.

load metamorphism
 * A type of static metamorphism in which pressure due to deep burial has been a controlling influence, along with high temperature. CF: thermal metamorphism. See also: static metamorphism.

load-out
 * To load coal or rock that is to be taken out of the mine.

loadstar
 * See: lodestone.

loadstone
 * Alternate spelling of lodestone. See also: lodestone.

load transfer
 * The weight of the strata above every excavation is largely transferred to the coal pillars or packs in the vicinity. Attempts are made to control and facilitate this load transfer in the yield-pillar system and in double packing. See also: abutment; pressure arch.

loam beater
 * A rammer used in making a loam mold.

loam cake
 * A disk of dried loam used to cover a loam mold; it has holes through which melted metal is poured and air escapes.

loaming
 * A method of geochemical prospecting in which samples of soil or other surficial material are tested for traces of the metal desired, its presence presumably indicating a near-surface orebody.

Lobbe Hobel
 * An earlier type of rapid plow traveling at 70 ft/min (21.3 m/min) across the face.

Lobbert lagging
 * A lagging consisting of galvanized steel wire frames fastened to underground haulageway supports by special wire fasteners to provide a continuous lining.

lobs
 * Steps in a mine.

local cell
 * A galvanic cell resulting from inhomogeneities between areas on a metal surface in an electrolyte. The inhomogeneities may be of physical or chemical nature in either the metal or its environment. See also: cell.

local current
 * A natural earth current of local origin, such as one arising from the oxidation of a sulfide deposit. A term used in electrical prospecting.

local extension
 * The extension produced in a tensile test after the ultimate tensile stress has been passed and concentrated on part of the gauge length where a neck is formed.

local indicator plant
 * Plants of wide geographic distribution having an affinity for absorbing certain metallic elements from the soil and which can be used in geochemical exploration to indicate presence of local concentrations of metals. CF: universal plant indicator.

local metamorphism
 * Metamorphism caused by a local process; e.g., contact metamorphism or metasomatism near an igneous body, hydrothermal metamorphism, or dislocation metamorphism in a fault zone. CF: regional metamorphism.

local shear failure
 * Failure in which the ultimate shearing strength of the soil is mobilized only locally along the potential surface of sliding at the time the structure supported by the soil is impaired by excessive movement.

local unconformity
 * An unconformity that is strictly limited in geographic extent and that usually represents a relatively short period, such as one developed around the margins of a sedimentary basin or along the axis of a structural trend that rose intermittently while continuous deposition occurred in an adjacent area. It may be similar in appearance to, but lacks the regional importance of, a disconformity. CF: regional unconformity.

local vent
 * A pipe or shaft to convey foul air from a plumbing fixture or a room to the outer air.

local ventilation
 * Ventilation of the drives and headings in mines by use of the pressure gradient of the main air current.

locatable minerals
 * A legal term that, for public lands in the United States, defines a mineral or mineral commodity that is acquired through the General Mining Law of 1872, as amended (30 U.S.C. 22-54, 161, 162, 611-615). These are the base and precious metal ores, ferrous metal ores, and certain classes of industrial minerals. Acquisition is by staking a mining claim (location) over the deposit and then acquiring the necessary permits to explore or mine.

location and patent
 * The location of a mining claim and patent for a mining claim are not governed by the same rules. The mining statutes expressly provide for the location of surface ground that must include the lode or claim as discovered; and a patent cannot grant any greater extent of surface ground than the location as made and marked by the surface boundaries.

location notice
 * A written notice prominently posted on a claim, giving name of locator and description of its extent and boundaries.

location plan
 * A map, drawn to a suitable scale, showing the proposed mine development, shafts, works, etc., in relation to existing surface features. See also: location.

location survey
 * See: location.

location work
 * Labor required by law to be done on mining claims within 60 days of location, in order to establish ownership. Syn: assessment work.

loch
 * An unfilled cavity in a vein. See also: vug.

lockage
 * Water consumed in passing from the upper reach of a canal when a vessel passes through a lock.

locked coil rope
 * Made of specially formed wires assembled in layers of alternate lay about a wire core, which gives a smooth rope, and the entire surface is available for resisting wear. Such ropes are used in the United States for track cables on aerial tramways, and in England as hoisting ropes collieries. See also: wire rope.

locked-cycle test
 * A series of repetitive batch tests in which the middling products generated in one test are added to the subsequent test to simulate the operations of a continuous process in which intermediate-grade materials are recycled. Each test is referred to as a "cycle." When equilibrium is reached in two or more cycles, depending on the sensitivity of the separation, the test is said to be "locked" or "balanced."

locked particles
 * Particles of coal or ore consisting of two or more minerals.

locked test
 * In laboratory tests on small quantities of ore, a method in which any selected fraction of the product is added to a fresh batch of the sample, so that the cumulative effect of its retention can be studied under conditions that simulate a continuous process in which middlings are recirculated or partly used water or leach liquor is returned. See also: cyclic test.

locked-wire rope
 * A rope with a smooth cylindrical surface, the outer wires of which are drawn to such shape that each one interlocks with the other and the wires are disposed in concentric layers about a wire core instead of in strands. Particularly adapted for haulage and rope-transmission purposes.

locker
 * A short piece of round timber or iron rod for inserting between the spokes of a tram wheel to retard its movement. Also called lolley; sprag.

locking bolts
 * Bolts of any type used for locking parts in position.

locknut
 * The nut securing the feed gears in the feeding mechanism in a gear-feed swivel head on a diamond drill; also, any extra nut used to secure a principal nut. Also called jamnut; jambnut.

lock paddle
 * A sluice whereby a lock chamber is emptied or filled.

lockpin
 * Any pin or plug inserted in a part to prevent play or motion in the part so fastened.

lock sill
 * A raised portion of the floor of a lock chamber, forming a stop against which the lock gates bear when they are shut.

lockup clutch
 * A clutch that can be engaged to provide a nonslip mechanical drive through a fluid coupling.

locomotive
 * An electric engine, operating either from current supplied from trolley and track or from storage batteries carried on the locomotive. The locomotive may be powered by battery, diesel, compressed air, trolley, or some combination such as battery-trolley or trolley-cable reel. Used to move empty and loaded mine cars in and out of the mine.

locomotive arches
 * Arches built of special refractory shapes, supported by water-circulating members.

locomotive brakeman
 * In anthracite and bituminous coal mining, one who works on trains or trips of cars hauled by locomotive or motor, as distinguished from rope haulage. Also called locomotive helper; locomotive patcher; motor brakeman; motor nipper; poleman.

locomotive garage
 * An elongated recess in an intake airway of a mine for servicing locomotives. It contains two or three rail tracks (with pit space under one), good lighting, lifting equipment, oils, benches, and tools. Where battery locomotives are used, the garage will serve as a charging station. Syn: underground garage; battery charging station.

locomotive gradient
 * The statutory maximum gradient for locomotive haulage is 1:15, but ordinarily the practical limit is about 1:25. Roads driven specially for locomotives are normally graded about 1:400 in favor of the load, unless a steeper gradient is required for drainage.

locomotive haulage
 * The transport of coal, ore, workers, and materials underground by means of locomotive-hauled mine cars. The locomotive may be powered by battery, diesel, compressed air, trolley, or some combination such as battery-trolley or trolley-cable reel. See also: compressed-air locomotive; haulage; underground haulage.

locomotive helper
 * See: locomotive brakeman.

locomotive pan brick
 * Shapes, used to build a burner enclosure, flash wall, and protecting walls for the water legs.

locomotive patcher
 * See: locomotive brakeman.

locomotive resistance
 * The combined resistance caused by the friction of the journal and the wheel tread. It can range from 12 to 20 lb (5.44 to 9.07 kg), but for practical purposes may be taken as 15 lb (6.8 kg), as the locomotive represents only a small portion of the total tractive effort.

lode
 * A mineral deposit consisting of a zone of veins, veinlets, disseminations, or planar breccias; a mineral deposit in consolidated rock as opposed to a placer deposit. Syn: lead. CF: vein; vein system. See also: vein or lode claim.

lode claim
 * a. That portion of a vein or lode, and of the adjoining surface, that has been acquired by a compliance with the law, both Federal and State. Any dispute as to whether a given parcel of land is a vein or a lode is a question of fact to be determined by those experienced in mining, and it cannot be determined as a matter of law.

b. See: vein or lode claim. c. A mining claim on an area containing a known vein or lode. CF: placer claim.

lode plot
 * A horizontal lode.

lodestone
 * a. A variety of magnetite showing spontaneous magnetization because of preferential alignment of magnetic domains within a crystal or mass of crystals. If permitted to do so, lodestone will align its polarity with the geomagnetic field, e.g., floating on a piece of wood in water as an early type of compass for navigation. Also spelled loadstone. Syn: leading stone; Hercules stone; loadstar.

b. An intensely magnetized rock or ore deposit. See also: magnetite.

lodestuff
 * Minerals included in a lode or vein, including economically valueless gangue. See also: veinstuff.

lode tin
 * Tin ore (cassiterite) occurring in veins, as distinguished from stream tin or placer tin. CF: stream tin.

lodge
 * a. A reservoir of any size used for holding water in a mine. A sump or standage. Also called lodgement. See also: pound.

b. Eng. A subterranean reservoir for the drainage of the mine made at the shaft bottom, in the interior of the workings, or at different levels in the shaft. c. Scot. A cabin at the mine shaft for workers. d. The room or flat at the shaft into which the pushers or trammers empty their loads. e. S Wales. The local branch of the coal miners' union. f. A pump room, near the pit bottom or other main pumping station.

lodgment level
 * Scot. A room driven from a level a short distance to the dip and used for storage of water. A sump.

loellingite
 * See: loellingite.

loess
 * A widespread, nonstratified, porous, friable, usually highly calcareous, blanket deposit (generally less than 30 m thick), consisting predominantly of silt with subordinate grain sizes ranging from clay to fine sand. It covers areas extending from north-central Europe to eastern China as well as the Mississippi Valley and Pacific Northwest of the United States. Loess is generally buff to light yellow or yellowish brown; often contains shells, bones, and teeth of mammals; and is traversed by networks of small narrow vertical tubes (frequently lined with calcium carbonate concretions) left by successive generations of grass roots, which allow the loess to stand in steep or nearly vertical faces. Loess is now generally believed to be windblown dust of Pleistocene age. CF: adobe.

loeweite
 * Alternate spelling of loeweite.

Loewinson-Lessing classification
 * A chemical classification of igneous rocks (into the four main types--acid, intermediate, basic, and ultrabasic) based on silica content.

Lofco car feeder
 * An appliance for controlling mine cars at loading points, for marshalling trains, and for loading cars into cages, tipplers, and other points. It consists of a carrying chain running between the rails. The dummy or live axles of the cars are held firmly by the chain's profile, and an overload slipping action is provided. See also: feeder.

lofthead
 * An overhead cavity caused by a fall of roof.

lofting
 * a. S. Wales. An old or disused heading over the top of another one.

b. N. of Eng. See: lacing. c. Scot. Wood filling up vacant space on top of crowns or gears. d. Timbers, usually old, laid across the caps of steel frames or sets in a working to support the roof.

log
 * The record of, or the process of recording, events or the type and characteristics of the rock penetrated in drilling a borehole, as evidenced by the cuttings, core recovered, or information obtained from electric, sonic, or radioactivity devices. Also called logged; logging. See also: well log. CF: logbook.

Logan slabbing machine
 * This machine consists essentially of two horizontal cutting chains, one working at the base of the coal seam and the other at a distance from the floor; a third cutter chain is mounted vertically on a shearing jib at right angles to the other two and shears off the coal at the back of the cut. The upper jib breaks the coal up into loadable size, and a short conveyor transfers it to the face conveyor. Similar in principle to the A.B. Meco-Moore cutter-loader.

logbook
 * A book in which the official record of events or the type and characteristics of the rock penetrated by the borehole is entered. Also called journal; journal book. CF: log.

logging chain
 * A chain composed of links of round bar pieces curved and welded to interlock, with a grabhook at one end and a round hook at the other.

logging tongs
 * Tongs with end hooks that dig in when the tongs are pulled.

log washer
 * A slightly slanting trough in which revolves a thick shaft or log, carrying blades obliquely set to the axis. Material is fed in at the lower end, water at the upper. The blades slowly convey the lumps of material upward against the current, while any adhering clay is gradually disintegrated and floated out the lower end.

Lohmannizing
 * A process by which a protective zinc coating is amalgamated to a base-metal sheet.

loipon
 * A term proposed by Shrock (1947) for a residual surficial layer produced by intense and prolonged chemical weathering and composed largely of certain original constituents of the source rock. Typical accumulations of loipon are the gossans over orebodies, bauxite deposits in Arkansas, terra rossa deposits of Europe, and duricrust of Australia. Etymol: Greek, residue. Adj: loiponic.

lok batanite
 * Variety of bituminous material derived from a mud volcano.

loellingite
 * a. An orthorhombic mineral, 2[FeAs (sub 2) ] ; basal cleavage; metallic; sp gr, 7.45; in quartz veins; a source of arsenic. Also spelled loellingite, lollingite. Syn: leucopyrite; glaucopyrite; geyerite.

b. The mineral group costibite, loellingite, nisbite, rammelsbergite, safflorite, and seinaejokite.

loma
 * A term used in the Southwestern United States for an elongated, gentle swell or rise of the ground (as on a plain), or a rounded, broad-topped, inconspicuous hill. Etymol: Spanish, hillock, rising ground, slope.

lomonosovite
 * A triclinic mineral, Na (sub 2) Ti (sub 2) Si (sub 2) O (sub 9) .Na (sub 3) PO (sub 4) ; in alkalic pegmatites and sodalite syenites; Kola Peninsula, Russia.

long awn
 * A direction of less than 45 degrees to the main natural line of cleat or cleavage in the coal. Also spelled horn. CF: short awn.

long clay
 * A highly plastic clay. Syn: fat clay.

long column
 * A column that fails by buckling, as distinct from crushing, when overloaded. CF: short column.

long hole
 * Underground boreholes and blastholes exceeding 10 ft (3.05 m) in depth or requiring the use of two or more lengths of drill steel or rods coupled together to attain the desired depth. CF: long-hole drill.

long-hole blasting
 * Method of blasting, employing diamond drills or extension steel drills with tungsten carbide bits, applied to ore-winning operations where conditions are suitable. The essential requirements from the practical and economic points of view are (1) a large orebody or wide regular vein, (2) a strong country rock, and (3) a good parting between the ore and the rock to avoid undue contamination of the ore. Holes to take cartridges up to 2 in (5.1 cm) in diameter may be drilled. Since the drilling of long holes is relatively expensive, high-strength, high-density gelatinous explosives are usually employed so that the maximum burden can be placed on each hole. For this reason also, the largest diameter of explosive cartridge that can be loaded into the holes should be used to obtain the greatest possible loading density.

long-hole drill
 * A rotary- or percussive-type drill used to drill underground blastholes to depths exceeding 3 m. CF: long hole.

long-hole infusion
 * There are two methods: (1) Long holes are drilled parallel to the coal face. Charges of Hydrobel explosive are spaced along the holes and fired under water pressure. The object is to loosen the coal and allay the dust along the entire face in one operation. See also: pulsed infusion shot firing. (2) Two or more holes are drilled about 40 ft (12.2 m) long in the line of advance of the workings. The holes are not charged with explosive and fired but only subjected to water pressure up to 3,000 psi (20.7 MPa) to loosen the coal and allay the dust in the cleats. The holes may be drilled during weekends and of a length about equal to the weekly advance of the face.

long-hole jetting
 * A hydraulic mining system consisting essentially of drilling a hole down the pitch of the vein, replacing the drilling head with a jet cutting head, and then retracting the drill column with the jets in operation to remove the coal. Coal cut loose by the jets drops to a flume drift and is carried by water to a screening and loading plant.

longitudinal fault
 * A fault whose strike is parallel with that of the general structural trend of the region.

longitudinal fissure
 * A fissure that is parallel with the strike of the deposit.

longitudinal joint
 * A steeply dipping joint plane in a pluton that is oriented parallel to the lines of flow. Syn: S-joint; bc-joint.

longitudinal trace
 * A trace on the ground motion record representing the component of motion in a horizontal plane and in the direction of the seismic wave travel direction. Syn: radial axis.

longitudinal valley
 * See: strike valley.

longitudinal velocity
 * See: modulus of elasticity.

longitudinal wave
 * An elastic wave in which the displacements are in the direction of wave propagation. Syn: P wave; primary wave.

long (lazy) flames
 * Partially aerated flames, particularly when aerated in stages. Nonturbulent flow.

Longmaid-Henderson process
 * Method of recovering copper from burned sulfides, by roasting with rock salt and using the issuing gases, after condensation, to leach the chloridized residue. Copper then dissolved is precipitated from the leach liquor onto scrap iron.

long piggyback conveyor
 * An appliance to provide a constant flow of coal from a continuous miner to the main haulage system. It consists of a conveyor slung under the tail end of the loader and running on a bogey straddling the heading conveyor so that it can telescope over it.

long-pillar work
 * Coal winning in three stages in underground mining. First, large pillars are left as the face is advanced by means of drives. Second, parallel drives connect these drives and form large blocks. Finally, the pillars so formed are mined.

long-range order
 * The property of crystal structures wherein atomic particles show periodicity over large numbers of atomic diameters and each atomic particle has specific relationships with lattice points. CF: short-range order; disorder. See: superlattice; superstructure.

long run
 * To fill or nearly fill the core barrel with core on a single trip into the borehole. CF: short run.

long-running thermal precipitator
 * A dust-sampling instrument designed by the Mining Research Establishment of Great Britain that operates over periods of up to 8 h and collects only respirable dust that is selected aerodynamically during the sampling process. The respirable fraction is selected by drawing the dust through a horizontal duct elutriator that simulates the acting principle of the human nose and respiratory passages in that the larger and faster-falling particles are caught by the processes of settlement and impingement.

long section
 * A section of land that contains more than 640 acres (256 ha).

long-shank chopping bit
 * A steel chisel-edged chopping bit having a longer and heavier-than-normal shank, designed to give added weight and directional stability when chopping an angle hole through overburden.

longshore current
 * A current in the surf zone, moving generally parallel to the shoreline, generated by waves breaking at an angle with the shoreline. Syn: littoral current.

longshore drift
 * See: beach drift.

long tom
 * A trough for washing gold-bearing earth. It is longer than a rocker.

longues tailles
 * Fr. See: longwall.

longwall
 * a. A long face of coal.

b. A method of working coal seams believed to have originated in Shropshire, England, toward the end of the 17th century. The seam is removed in one operation by means of a long working face or wall, thus the name. The workings advance (or retreat) in a continuous line, which may be several hundred yards in length. The space from which the coal has been removed (the gob, goaf, or waste) either is allowed to collapse (caving) or is completely or partially filled or stowed with stone and debris. The stowing material is obtained from any dirt in the seam and from the ripping operations on the roadways to gain height. Stowing material is sometimes brought down from the surface and packed by hand or by mechanical means. See also: longwall advancing; longwall retreating. Also known as longwork; Shropshire method; combination longwall; and Nottingham or Barry system. Syn: combination longwall. c. Opposite of shortwall. See also: longwall mining.

longwall advancing
 * A system of longwall working in which the faces advance from the shafts toward the boundary or other limit lines. In this method, all the roadways are in worked-out areas. See also: longwall.

longwall coal cutter
 * Compact machine, driven by compressed air or electricity, that cuts into the coal face with its jib at right angles to its body. See also: longwall machine.

longwall machine
 * A power-driven machine used for shearing coal on relatively long faces. See also: longwall coal cutter.

longwall miner
 * In bituminous coal mining, one who extracts coal from seams by a specialized method known as longwall mining. In this method, all coal is extracted as the work progresses, and the roof caves behind the working face.

longwall mining
 * a. A full-extraction method for mining large panels of coal.

b. A system of mining in which all the minable coal is recovered in one operation. c. A method of mining flat-bedded deposits, in which the working face is advanced over a considerable width at one time. See also: longwall.

longwall peak stoping
 * A method of underland stoping in which rapid advance of the face is maintained, and by working the faces at an angle of 60 degrees to the strike, the peak travels down the dip at twice the rate of the face advance. This method was introduced on the Witwatersrand for stoping below 5,000 ft (1,524 m), where rapid face advance resulting from the closer spacing of holes reduces the incidence of rock bursts.

longwall pillar working
 * The extraction of the coal pillars formed by a pillar method of working, by a longwall face, which can be advancing or retreating. Where the crush is not excessive, this method is more efficient and often safer than extracting each pillar individually.

longwall retreating
 * A system of longwall working in which the developing headings are driven narrow to the boundary or limit line and then the coal seam is extracted by longwall faces retreating toward the shaft. In this method, all the roadways are in the solid coal seam and the waste areas are left behind. See also: longwall; mechanized heading development.

lonkey
 * Eng. The best Yorkshire sandstone, Rossendale District. CF: lunker.

loodwin
 * Burma. Ruby mines in which fissures, caves, and hollows in the limestone, filled with detritus from its disintegration, are followed, and their contents, often cemented or buried under recent travertine, are extracted and washed.

looking-glass ore
 * Lustrous hematite, Fe (sub 2) O (sub 3) . Specular iron ore; iron glance. Mohs hardness, 6; sp gr, 5.2.

lool
 * A vessel to receive ore washings.

loom
 * Eng. A variant of loam, esp. in the Thames Valley; applied to Thanet sand and dredged mud used for cement.

loop circuit
 * A term used when two positive wires are installed in divergent directions but later come close enough together to be connected. They then form a series or so-called loop circuit. CF: parallel blasting circuit.

loop drag
 * An eye at the end of a rod through which tow is passed for cleaning boreholes.

looper
 * In ore dressing, smelting, and refining, a laborer who attaches loops (folded copper sheets or strips) to starting sheets so that sheets can be suspended in electrolytic tanks. Also called looper puncher.

loop haulage
 * A system used when a continuous supply of cars must be supplied to a loading station. In this system, the empty cars are simply coupled to one end of the standing cars, which are pulled forward by a hoist with the rope attached to a clip fixed to the side of the cars. The rope is pulled back by hand for a distance of three or four car-lengths, and the process is repeated frequently as the end of the rope approaches the hoist.

looping
 * The running together of ore matter into a mass when the ore is only heated for calcination. CF: loup.

looping mill
 * Consists of one or more trains of alternating two-high stands. As the piece being rolled emerges from one stand, it is turned through 180 degrees and entered into the next stand and similarly into the succeeding stands. In some mills, the looping is performed by hand, while in others it is done mechanically by means of repeaters or looping channels.

loop-type pit bottom
 * A pit bottom layout in which the loaded cars are fed to the cage from one side only and the empties are returned to the same side by means of a loop roadway. The loop arrangement provides more standage room for cars and is more suitable for multideck cages. When the coal reaches the pit bottom from two sides, a double-loop layout may be adopted.

loopway
 * A double-track loop in a main single-track haulage plane at which mine cars may pass. A loopway located close to the face or loading machine enables a train of empty cars to be stationed in the loop, while the loaded cars are run straight out on the main single track.

loose
 * Loose, or crick, is a vertical joint affecting only the lower strata in a oolite quarry, Northamptonshire, U.K. Syn: crick.

loose end
 * a. A gangway in longwall working, driven so that one side is solid ground while the other opens upon old workings. CF: fast end.

b. Coal prepared by cutting, or that coal that is certain to be loosened by a shot. c. The limit of a stall next to the goaf, or where the adjoining stall is in advance.

loose goods
 * Industrial diamonds as purchased from a diamond supplier in bulk. CF: loose stone.

loose ground
 * a. Broken, fragmented, or loosely cemented bedrock material that tends to slough from sidewalls into a borehole. Also called broken ground. CF: breccia. Syn: loose rock.

b. As used by miners, rock that must be barred down to make an underground workplace safe; also fragmented or weak rock in which underground openings cannot be held open unless artificially supported, as with timber sets and lagging. CF: broken ground. c. A shattered rock formation, or a formation crisscrossed with numerous, closely spaced, uncemented joints and cracks.

loose-needle traversing
 * A method of traversing in which the magnetic bearings of survey lines are separately obtained by reference to the magnetic needle.

loosening bar
 * An implement for loosening a pattern from a sand mold.

loose rails
 * Aust. Rails that can be lifted and placed across a permanent line when desired to run skips across it.

loose rock
 * See: loose ground.

looses
 * Vertical joints affecting only the lower strata in the ooelite quarries, Northamptonshire, U.K. Also called cricks.

loose stone
 * a. A diamond insecurely bonded in a bit matrix.

b. A diamond detached from a bit and lying on the bottom of a drill hole. c. An unset industrial diamond. CF: loose goods.

loose yards
 * Measurement of soil or rock after it has been loosened by digging or blasting.

loosing
 * S. Staff. Lowering a cage, etc., into a shaft or pit.

loparite
 * A possibly orthorhombic mineral, (Ce,Na,Ca) (sub 2) (Ti,Nb) (sub 2) O (sub 6) ; perovskite group; pseudocubic; Kola Peninsula, Russia.

lopezite
 * A triclinic mineral, K (sub 2) Cr (sub 2) O (sub 7) ; forms minute orange-red balls in nitratine in Chile.

lopolith
 * A large, concordant, typically layered igneous intrusion, of planoconvex or lenticular shape, that is sunken in its central part owing to sagging of the underlying country rock. Syn: funnel intrusion.

loran
 * Any of various long-range radio position-fixing systems by which hyperbolic lines of position are determined by measuring the difference in arrival times of synchronized pulse signals from two or more fixed transmitting radio stations of known geographic position. Loran fixes may be obtained at a range of 1,400 nmi (2,593 km) at night. CF: shoran. Etymol: long-range navigation.

lorandite
 * A monoclinic mineral, TlAsS (sub 2) ; red; forms modified tabular or prismatic crystals with one perfect cleavage.

loranskite
 * A mineral, (Y,Ce,Ca)ZrTaO (sub 6) (?).

lorettoite
 * A tetragonal artifact, Pb (sub 7) O (sub 6) Cl (sub 2).

lorry
 * a. York. A movable bridge over a shaft top upon which the bucket is placed after it is brought up for emptying.

b. A car used on mine tramways, or at coke ovens. c. Gr. Brit. A long wagon having a very low platform and four very small wheels.