Appendix:Dictionary of Mining, Mineral, and Related Terms/M/6

muck bar
 * Gray, forge pig iron melted in a puddling furnace, then balled, squeezed, and rolled.

muck boss
 * In bituminous coal mining, a person who is in charge of a crew of loaders shoveling rock into cars during the driving of new underground passageways from one part of the mine to another.

mucker
 * In mining and quarrying, a laborer who (1) shovels ore or rock into mine cars or onto a conveyor from which mine cars are loaded and at some point are removed from the working face or surfaces of natural stone deposits; or (2) works in a stope shoveling ore into chutes from which it is loaded into cars on haulage level below. Also called car filler; rock passer; shoveler.

mucking
 * The operation of loading broken rock by hand or machine, usually in shafts or tunnels.

muck iron
 * Crude puddled iron ready for squeezing or rolling.

muckle
 * Soft clay overlying or underlying coal.

muckle hammer
 * A scaling or spalling hammer.

muck saw
 * A saw using an uncharged blade, usually steel, which runs in a bath or stream of carborundum abrasive. Also known as a mud saw.

muck shifting
 * Operations concerned with stripping overburden, valuable gravels, or sands in exploitation of opencast mineral deposits.

muck soil
 * A soil that contains at least 50% organic matter that is well decomposed.

mucky hole
 * In a furnace, a taphole from which the iron is so pasty that it does not run freely.

mud
 * a. A sticky or slippery mixture of water and silt- or clay-sized earth material, with a consistency ranging from semifluid to soft and plastic; a wet, soft soil or earthy mass; mire, sludge.

b. An unconsolidated sediment consisting of clay and/or silt, together with material of other dimensions (such as sand), mixed with water. c. A suspension made by mixing the drill circulation fluid (water) with the fine cuttings produced by the bit when drilling a borehole.

mud auger
 * A diamond-point bit with the wings of the point twisted in a shallow, augerlike spiral. Also called clay bit; diamond-point bit. See also: mud bit.

mud balance
 * An instrument used to measure the density of drill mud.

mud barrel
 * a. A double-tube core barrel with a greater-than-normal clearance between the inner and outer tubes, for use with mud-laden circulation liquids.

b. A bailing device to bring to the surface the cuttings formed by the action of the bit at the bottom of a borehole in free-fall or churn drilling. c. A small bailer.

mud belt
 * The belt of marine deposits composed largely of detrital clay, and lying between the coarser terrigenous sediments to the landward and the deep oceanic organic oozes on the seaward side. At present, the inner boundary of the inner mud belt is the edge of the continental shelf.

mud bit
 * A pointed-edge, chisellike tool used for boring drill holes through clay or claylike overburden materials. Also called clay bit; diamond-point bit. See also: mud auger.

mud blasting
 * In this method, sticks of explosive are stuck on the side of a boulder with a covering of mud, and when detonated, very little of the energy of the explosive is used in breaking the boulder.

mud bucket
 * The bucket attached to a dredger.

mud cake
 * The material filling the cracks, crevices, pores, etc., of the rock or adhering to the walls of a borehole. The cake may be derived from the drill cuttings, circulating drill mud, or both; it is formed when the water in the drilling mud filters into porous formations, leaving the mud ingredients as a caked layer adhering to the walls of the borehole. Syn: cake; mud wall cake.

mudcap
 * A charge of dynamite, or other high explosive, fired in contact with the surface of a rock after being covered with quantity of wet mud, wet earth, or sand, no borehole being used. The slight confinement given the dynamite by the mud or other material permits part of the energy of the dynamite being transmitted to the rock in the form of a blow. A mudcap may be placed on top or to one side, or even under a rock, if supported, with equal effect. Also called adobe; dobie; sandblast.

mudcap method
 * See: secondary blasting.

mudcapping
 * Method for blasting rock without drilling, in which an explosive is placed on top of the rock and covered by a cap of mud or earth. Syn: adobe charge.

mud cast
 * See: mud crack.

mud column
 * The length in feet (meters), as measured from the bottom of a borehole of a drill-mud liquid standing in a borehole either while being circulated during drilling operations or when the drill string is not in the hole. Syn: column of mud.

mud crack
 * a. The filling of desiccation cracks in mud, customarily in sandstone; generally preserved as raised ridges (casts) arranged in polygonal patterns on the underside of a sandstone bed.

b. An irregular fracture in a crudely polygonal pattern, formed by the shrinkage of clay, silt, or mud, generally in the course of drying. Syn: sun crack; mud cast; shrinkage crack; desiccation crack.

mudding
 * Filling voids with clay in limestone from which sulfur has been extracted.

mudding off
 * In petroleum production, commonly thought of as reduced productivity caused by the penetrating, sealing, or plastering effect of a drilling fluid. Actually there is little penetration into the capillaries of an ordinary producing formation, and a slight amount of differential back pressure will remove even thick filter cakes.

mudflow
 * A general term for a mass-movement landform and a process characterized by a flowing mass of predominantly fine-grained earth material possessing a high degree of fluidity during movement. The water content of mudflows may range up to 60%. With increasing fluidity, mudflows grade into loaded and clear streams; with a decrease in fluidity, they grade into earthflows. Syn: lahar.

mud gun
 * An apparatus for pushing a clay stopper into the taphole of a blast furnace. A steam cylinder operates a plunger inside a steel tube into which clay is fed from a hopper tube as the plunger is worked back and forth, and is thus forced into the taphole at the end of a cast. See also: clay gun.

mud hog
 * a. A pump used to circulate mud-laden drill fluid during borehole drilling operations. See also: mud pump; sludge pump.

b. Pressure tunnel worker. c. A machine for the disintegration of dry or moist plastic clay. It consists of a rotating swing hammer operating close to a series of anvils linked together to form a steeply inclined slat conveyor.

mud-laden
 * Said of a liquid (usually water) mixed with finely ground earthy or clayey materials.

mud-laden fluid
 * The water or oil in which mudlike solids are suspended; used to support the open bore and cool and clear the cuttings from a drill bit. The fluid is circulated while rotary- and/or diamond-drilling a borehole. See also: drilling mud.

mudline
 * Line of demarcation between fairly clear supernatant water and settling solids in a thickener or other sedimentation vessel.

mud log
 * A continuous analysis of the drilling mud and well cuttings during rotary drilling for entrained oil or gas. Visual observation, ultraviolet fluoroscopy, partition gas chromatograph, and hydrogen-flame ionization analyzer may be used. A drilling-time log is kept concurrently.

mud logging
 * a. A method of determining the presence or absence of oil, gas, and salt water in the various formations penetrated by a drill bit. The drilling fluid and the cuttings are continuously tested on their return to the surface, and the results of these tests are correlated with the depth of origin.

b. A mud log is a recording vs. depth of the parameters being monitored. Basic parameters monitored are: bit weight, rotary speed, rotary torgue, mud weight, gas content (trip and background) cutting analysis, pit volume, flow rate, pump pressure (strokes), hole depth, and chlorides. This is a common service used to obtain data from the mud system and drilling parameters.

mud mixer
 * A machine, pump, hopper, or other apparatus used to mix dry ingredients with water or other liquids to prepare a drill mud. Also called atomizer; jet mixer; mixer. Syn: emulsifier.

mud pot
 * a. A type of hot spring containing boiling mud, usually sulfurous and often multicolored, as in a paint pot. Mud pots are commonly associated with geysers and other hot springs in volcanic areas, esp. Yellowstone National Park, WY.

b. A geyser that throws up mud. Also called mud geyser.

mud pump
 * a. The circulating pump that supplies fluid to a rotary drill. Also called slush pump. See also: mud hog.

b. See: circulating pump.

mud ring
 * a. The section of a boiler where scale, alkalies, and sediment collect.

b. The ring or frame forming the bottom of a water leg in a steam boiler.

mud rush
 * The more or less sudden inflow of peat, moss, sand, gravel, silt, or any other waterlogged material into shallow mine workings. The manager has a duty to take steps to prevent such inrushes as laid down in the Precautions against Inrushes Regulations, 1956. Also called mud run. See also: inrush of water; running ground.

mud scow
 * A flatboat or barge for the transportation of mud, generally used in connection with dredges.

mud snapper
 * An 11-in-long (28-cm-long), 3-lb (1.4-kg) clamshell-type snapper attached to the bottom of a sounding lead by means of a hole drilled in the lead. The jaws are cast bronze and are actuated by a spring. The jaws are held open by engaging two trigger pins within the jaws. The mud snapper and sounding lead may be operated in shallow water by hand lowering or by lowering from a bathythermograph or oceanographic winch.

mud socket
 * A device attached to drill rods and used to remove sand from a borehole. CF: mule shoe.

mudstone
 * a. An indurated mud having the texture and composition of shale, but lacking its fissility; a blocky or massive, fine-grained sedimentary rock in which the proportions of clay and silt are approx. equal; a nonfissile mud shale. See also: claystone; siltstone.

b. A general term that includes clay, silt, claystone, siltstone, shale, and argillite.

mudstone ratio
 * A uranium prospector's term, esp. on the Colorado Plateau, for the ratio of the total thickness of red mudstone to that of green mudstone within an assumed stratigraphic interval. Its value is based upon the premise that uranium-bearing solutions will bleach red mudstone containing ferric iron to green mudstone containing ferrous iron in the course of depositing uranium minerals.

mudstone trap
 * A place where uranium mineralization has been trapped at a mudstone-sandstone interface.

mud sump
 * In drilling operations, a mud pit.

mud up
 * a. The act or process of filling, choking, or clogging the waterways of a bit with consolidated drill cuttings. Also called sludging; sludging up.

b. The act or process of filling the pores or cracks in the rock surrounding a borehole; also, to cause mud to adhere to the walls of a borehole.

mud viscosity
 * The property of a mud-laden fluid to resist flow due to internal friction and the combined effects of adhesion and cohesion; e.g., a Marsh funnel (used to measure the viscosity of mud) will discharge 1 quart (0.95 L) of water in about 36 s, whereas an equal volume of an average drilling mud is discharged in 40 to 55 s or more from the same funneI.

mud volcano
 * An accumulation, usually conical, of mud and rock ejected by volcanic gases; also, a similar accumulation formed by escaping petroliferous gases.

mud wall cake
 * a. See: mud cake.

b. The formation of mud in the drilling fluid by adhering to the wall of the hole. When the drilling mud particles comes in contact with porous, permeable formation, solid particles immediately enter the openings. This sealing property is dependent upon the amount and physical state of the colloidal material in the mud.

muffle
 * a. A semi-cylindrical or long, arched oven (usually small and made of fireclay), heated from outside, in which substances may be exposed at high temperature to an oxidizing atmospheric current, and kept at the same time from contact with the gases from the fuel. Cupellation and scorification assays are performed in muffles; on a larger scale, copper ores were formerly roasted in muffle furnaces.

b. An enclosure in a furnace to protect the ware from the flame and products of combustion.

muffle furnace
 * a. A furnace with an externally heated chamber, the walls of which radiantly heat the contents of the chamber.

b. A furnace in which heat is applied to the outside of a refractory chamber containing the charge. The charge may be held in a muffle, crucible retort, or other enclosure that is enveloped by the hot flame gases, and the heat must reach the charge by flowing through the walls of the container.

muffle kiln
 * a. An arched fireclay-lined furnace in which seggars are placed.

b. A kiln in which combustion of the fuel takes place within refractory muffles, which, in turn, conduct heat into the ware chamber.

muffler
 * A muffler that concentrates on suppressing sound waves vibrating 200 to 2,000 times a second--the loudest and most objectionable ones created by rock drills. Because the muffler bypasses the lower frequencies, it does not interfere with the column of air that makes a pneumatic drill function.

mugearite
 * Orthoclase-bearing oligoclase basalt, with major olivine, accessory apatite, and opaque oxides. Pyroxene may or may not be present. See also: trachyandesite.

mule
 * a. A small car, or truck, used to push cars up a slope or inclined plane.

b. See: pusher. c. An extra worker who helps push the loaded cars out in case of an upgrade, etc.; from Joplin, Mo.

mule's foot
 * Kansas. An extension bit used in boring coal.

mule shoe
 * A short length of tubing coupled to the bottom of a drill string to wash and clean out sand or mud from a borehole, the washing action being aided by cutting off the bottom end of the tubing at an angle of 45 degrees to its longitudinal axis. Also called mud socket.

mule skinner
 * A mule driver.

muleway
 * Heavily timbered passage between levels in a mine for the transfer of unattached mules from one level to the other.

muller
 * a. Stone, iron shoe, or heavy steel rubbing disk, used to bear down upon rock in comminution.

b. A heavy grinding wheel that is the crushing and mixing member in a dry or wet pan. c. See: bucking iron.

mulling
 * Mixing sand and clay particles by a rolling, grinding, rubbing, or stirring action.

mullion structure
 * A wavelike pattern of parallel grooves and ridges, measuring as much as several feet from crest to crest, and formed on a folded surface or along a fault surface. CF: slickensides.

mullite
 * An orthorhombic mineral consisting of an aluminum silicate that is resistant to corrosion and heat; used as a refractory. Also known as porcelainite.

mullock
 * See: muck.

multibucket excavator
 * A machine similar to a dredger used for excavating cuttings for roads, railways, or canals. One large machine of this type can dig 100 yd/h (91.4 m/h) on a slope 25 ft (7.62 m) high.

Multicut chain
 * Trade name for a coal-cutter chain designed for use with curved jibs. It is short pitch and of high flexibility. See also: curved jib.

multideck cage
 * A cage containing two or more compartments or platforms to hold the mine cars supplies or workers. Every effort is made to keep the number of decks as low as possible for a given output in order to cut down the decking time and equipment at shaft top and bottom. See also: deck.

multideck screen
 * A screen with two or more superimposed screening surfaces mounted rigidly within a common frame.

multideck sinking platform
 * A sinking platform consisting of several decks to enable various shaft-sinking operations to be performed simultaneously. The bottom deck, in a three-deck platform, is usually suspended from four winch ropes which also act as guides for the kibbles, and the middle and top decks are supported above the bottom deck by rigid supports. The top deck is used for the manipulation of the concrete buckets and for fixing the shuttering. The center deck is used by the workers when placing the concrete, while the bottom deck carries telephone, blasting, lighting, and signaling cable drums. The lower side of the bottom deck may carry the equipment for manipulating the cactus grab.

multideck table
 * Shaking table with two or more superposed decks, independently fed and discharged but worked by one vibrating mechanism.

multifuse igniter
 * A device employed to reduce the number of fuses to be lit by the miner before retiring to safety. By means of a multifuse igniter, it is possible to remotely fire stopes or headings primed with plain detonators and safety fuse.

multihearth furnace
 * Roasting furnace with several hearths vertically superposed. Material is raked downward by horizontally rotating rabbles, so as to work alternately to the periphery and center of successive hearths, encountering roasting heat as it gravitates downward.

multijib cutter
 * A cutter loader with a number of horizontal jibs similar to a coal cutter. Loose coal is diverted onto the conveyor by gummer and plow plate. The machine is usually used in seams up to about 3 ft (0.9 m) in thickness with a clean roof parting. The depth of cut varies up to 4 ft (1.2 m). Coal degradation is considerable.

multilayer bit
 * A bit set with diamonds arranged in successive layers beneath the surface of the crown. CF: impregnated bit; surface-set bit.

multilock lode
 * Lode that occupies a shear zone. Such a zone has no definite walls, the ore gradually shading off into country rock. It is probable that the gold of some rich alluvial fields came from shear zones.

multilouvre dryer
 * A dryer whose moving element consists of two strands of roller chain with specially designed flights, suspended in such a way as to provide means for keeping the bed in a constantly flowing mass. The material flows in a shallow bed over the ascending flights and at the same time is gradually moved across the dryer from the feed point to the discharge point. The gases are pulled from the furnace and through the flowing bed of coal. The entire area of the dryer is covered by suction from the exhaust fan. See also: thermal drying.

multiphase
 * See: polyphase.

multiple-arch dam
 * A lightweight dam constructed of repeated arches with axes sloping at about 45 degrees to the horizontal, the arches being carried on parallel buttress walls.

multiple-bench quarrying
 * The method of quarrying a rock ledge in a series of successive benches or steps.

multiple detectors
 * Two or more seismic detectors whose combined output energy is fed into a single amplifier-recorder circuit. This technique is used to cancel undesirable near-surface waves. Syn: multiple geophones; multiple recording groups.

multiple dike
 * A dike made up of two or more intrusions of the same kind of igneous rock.

multiple-entry system
 * A system of access or development openings, generally in bituminous coal mines, involving more than one pair of parallel entries, one for haulage and fresh air intake and the other for return air. Multiple-entry systems permit circulation of large volumes of air.

multiple-expansion engine
 * An engine driven by steam or compressed air expanding in two or more stages.

multiple fault
 * A structure consisting of several parallel faults in close proximity with no distortion. See also: step fault.

multiple firing
 * Firing electrically with delay blasting caps in a number of holes at one time.

multiple fuse-igniter cartridge
 * Consists of a cardboard cartridge about 2 in long with a 3/4-in (1.9-cm) outside diameter. The closed end is coated with black powder, and the ends of eight fuses are inserted in the cartridge, in contact with the powder. A master fuse is then inserted, which, when lit, burns to the powder and ignites it. The powder flares brightly and lights the eight fuses.

multiple geophones
 * See: multiple detectors.

multiple intersections
 * a. The intercepts that cross a vein, orebody, or other geologic feature, accomplished by drilling several auxiliary boreholes from a single, main, or parent borehole with the aid of wedges and similar deflecting devices.

b. Intercepting a steeply dipping vein at various depths by changing the angle of the drill head.

multiple intrusion
 * Any type of igneous intrusion that has been produced by several injections separated by periods of crystallization. Chemical composition of the various injections is approx. the same. CF: composite intrusion.

multiple lines
 * A single line reeved around two or more sheaves so as to increase pull at the expense of speed.

multiple openings
 * Any series of underground openings separated by rib pillars or connected at frequent intervals to form a system of rooms and pillars.

multiple-ply plate
 * Steel plate made up of thicknesses of other plates of steel or steel and wrought iron welded together.

multiple recording groups
 * See: multiple detectors.

multiple ribbon belt conveyor
 * A belt conveyor having a conveying surface of two or more spaced strands of narrow flat belts.

multiple-row blasting
 * The drilling, charging, and firing of several rows of vertical holes along a quarry or opencast face. The holes may be spaced in the square pattern with delay detonators in the rows as well as row by row. The spacing of the holes will vary according to their depth, diameter, and the type of rock. See also: small-diameter blastholes.

multiple-seam mining
 * Mining two or more seams of coal, frequently close together, that can be mined profitably where mining one alone would not be profitable.

multiple seismometers
 * See: bunched seismometers.

multiple series
 * A method of wiring a large group of blasting charges by connecting small groups in series and connecting these series in parallel. Syn: parallel series.

multiple shooting
 * The firing of an entire face at one time. The holes are connected in a single series and all the holes shoot at the same instant.

multiple shot
 * See: battery of holes.

multiple-shot blasting unit
 * A multiple-shot blasting unit is designed for firing simultaneous explosive charges in mines, quarries, and tunnels. Syn: blasting unit.

multiple shotholes
 * Two or more shotholes that are shot almost simultaneously. They are so spaced as to minimize near-surface interferences that mask desired signals if only one shothole is used.

multiple-shot instrument
 * A borehole-survey instrument capable of taking and recording a series of inclination and bearing readings on a single trip into a borehole. CF: single-shot instrument.

multiple-shot survey
 * A borehole survey using a multiple-shot instrument.

multiple sill
 * A sill made up of two or more intrusions composed of the same kind of igneous rock.

multiple-speed floating control system
 * As used in flotation, a form of floating control system in which the manipulated variable may change at two or more rates each corresponding to a definite range of values of the actuating signal.

multiple splitting
 * The parting or separation of a thick seam into more than two layers of coal. See also: simple split seam.

multiple-strand chain
 * A roller chain made up of two or more strands assembled as a single structure on pins extending through the entire assembly.

multiple-strand conveyor
 * a. Any conveyor which employs two or more spaced strands of chain, belts, or cords as the load-supporting medium.

b. Any conveyor in which two or more strands are used as the propelling medium connecting pans, pallets, etc.

multiple-strand rope
 * A wire rope designed to obviate spinning due to untwisting. It is formed by a series of layers of strands built around a center fiber core. Each layer of strands is given a lay opposite to that on which it is built, each layer thus tending to impart its own twist that is cancelled by the next layer. Therefore, this rope can be used for sinking or where a free load is to be lifted. The stretch with a multiple strand rope is not so great as with round strand and flattened strand ropes. See also: multistrand rope; wire rope.

multiple twin
 * See: repeated twinning.

multiple-vent basalt
 * See: shield basalt.

multiple wedge
 * See: plug-and-feather method.

multiplow
 * A layout consisting of six or more plows, 220 lb (100 kg) each, 20 yd (18.3 m) apart on one rope or chain, feeding onto an armored conveyor; the load on the conveyor is well distributed. A driving unit is arranged at both ends of the face and operated alternately to impart a to-and-fro movement to the plows. The minimum workable seam thickness is 20 in (50.8 cm) at gradients from 0 degrees to 20 degrees ; maximum length of face is about 190 yd (174 m). See also: Gusto multiplow.

multiplying constant
 * The constant, used in stadia work, by which the staff intercept is multiplied to determine the distance between the staff and the theodolite. The value is generally taken as 100. See also: tachymeter.

multirope friction winder
 * A winding system based on the principles of the Koepe winder. The drive to the winding ropes is the frictional resistance between the ropes and the driving sheaves. Multirope friction winders are usually tower mounted, with either cages or skips, and provided with a counterweight. The sheaves are from about 6 to 12 ft (1.8 to 3.7 m) in diameter with a direct coupled or geared drive. Four ropes are favored and these operate in parallel and share the total suspended load. The system was introduced partly because of the difficulty of winding heavy loads from deep shafts with a single large-diameter winding rope. Modern winding ropes have become large and heavy, being 2-1/4 in (5.72 cm) in diameter locked coil, weighing 16.5 st (15 t) for a 1,000-yd (915-m) shaft; therefore, the introduction of the friction winder, with its counterweight, and using four smaller ropes side by side in place of one. Such ropes need be only 1-1/4 in (3.2 cm) in diameter to give equivalent breaking strain. See also: Koepe winder.

multishot firing
 * The firing of a number of shots simultaneously. See also: M.E. 6 exploder.

multishot gyroscopic instrument
 * A borehole surveying instrument that can take a number of readings during its descent and ascent in the borehole. It comprises gyroscopic and photographic recording units; direction and inclination indicators; a timing clock, and other accessories. A movie film enables numerous records to be taken throughout the depth of the borehole. See also: gelatin borehole tube.

multispectral scanner
 * A remote sensing device that is capable of recording data in the ultraviolet, visible, and infrared portions of the spectrum. Syn: shuttle multispectral infrared radiometer. See also: thematic mapper.

multistage fan
 * A fan having two or more impellers working in series.

multistrand rope
 * A flexible, nonspinning rope; composed of concentric layers of strands of relatively fine wires, alternate layers of strands being wound in opposite directions over a hemp core. See also: multiple-strand rope.

multiwheel roller
 * A heavy roller with pneumatic tires used to consolidate embankments.

mummification
 * The process of preservation of plant tissues under the influence of arrested decay.

mun
 * Corn. Any fusible metal.

mundic
 * A drillers' term for pyrite. See also: pyrite.

Munroe effect
 * The concentration of explosive effect (i.e. jetting) which occurs at a cavity at the end of an explosive charge; this effect is the basis of the design and performance of shaped charges.

muon
 * Contraction of mu-meson. An elementary particle with 207 times the mass of an electron. It may have a single positive or negative charge.

Murakami's reagent
 * An etching reagent developed for use in the investigation of the structure of iron-carbon-chromium alloys. It consists of a solution of 10 g potassium ferricyanide, 10 g potassium hydroxide, and 100 mL water.

murasakite
 * A schistose rock composed of piedmontite and quartz. See also: ollenite.

murdochite
 * An isometric mineral, PbCu (sub 6) O (sub 8) (Cl,Br) (sub 2) ; rare; secondary; forms minute black octahedra.

Murex process
 * A flotation process that is not strictly of the same class as others, but still makes use of the principle of selective oiling of sulfide particles. The crushed ore is fed into an agitator and mixed with 4% to 5% of its weight of a paste made of one part of oil or thin tar with three or four parts of magnetic oxide of iron. This oxide must be ground to an impalpable powder. These ingredients, with enough water to make a pulp, are agitated for 5 to 20 min. The paste preferentially adheres to the sulfides because of the oil. The ore is then fed over magnets, and oxide of iron, with the mineral adhering to it, is pulled out. The oil and magnetite are then recovered.

Muschamp coal miner
 * A cutter loader which is essentiaily a conversion unit for Anderton shearer machines and designed to produce a reasonable percentage of large coal. The top and bottom of the seam are cut by rotating drums of small diameter while shearing the back of the cut with a narrow-kerf jib and chain.

muscovado
 * A term applied in Minnesota to rusty-colored outcropping rocks, such as gabbros and quartzites, that resemble brown sugar. Etymol: Spanish, brown sugar.

muscovite
 * A monoclinic mineral, KAl (sub 2) (Si (sub 3) Al)O (sub 10) (OH,F) (sub 2); mica group; pseudohexagonal; perfect basal cleavage; forms large, transparent, strong, electrically and thermally insulating, stable sheets; a common rock-forming mineral in silicic plutonic rocks, mica schists, gneisses, and commercially in pegmatites; also a hydrothermal and weathering product of feldspar and in detrital sediments. Also spelled: moscovite. Syn: isinglass; white mica; potash mica; common mica; Muscovy glass; mirror stone. Sericite is fine-grained muscovite, commonly in connection with hydrothermal alteration, but sericite also includes paragonite and illite. Illite is a common syn. for fine-grained muscovite in clay mineralogy.

Muscovy glass
 * See: muscovite.

mushroom jib
 * A standard form of coal cutter jib with a sprocket at the end remote from the machine. The sprocket carries a vertical turret or bar and is driven by the cutting chain. The bar makes a vertical cut at the back of the normal horizontal cut. See also: turret jib.

muskeg
 * A bog, usually a sphagnum bog, frequently with grassy tussocks, growing in wet, poorly drained boreal regions, often areas of permafrost. Tamarack and black spruce are commonly associated with muskeg areas. Syn: maskeeg.

mussel bed
 * A band containing or chiefly composed of mussellike shells, very valuable in the correlation of Coal Measures strata.

Musso process
 * A mixture of iron ore and fuel is reduced in an externally heated rotary retort. The gases are exhausted and constitute the fuel when the process has been started. The gases, after purification, are passed through combustion rings surrounding the retort and are burned according to the method of catalytic combustion. After reduction, the charge is cooled when it is poured through a layer of fluxing material; it is then transferred to a steelmaking furnace.

mustard gold
 * A spongy type of free gold found in the gossan above gold-silver-telluride deposits.

mutabilite
 * A soft corklike bitumen of porous or resinous consistency. Partly soluble in organic solvents.

muthmannite
 * A mineral, (Ag,Au)Te ; soft; heavy; gray-white; in tabular crystals with perfect cleavage; an ore mineral.

mutu
 * A Malayan term denoting the degrees of fineness of gold.

mutual boundary texture
 * A rock texture showing smooth, regular, curved contacts between minerals.

mvb
 * Abbrev. for medium-volatile bituminous. See also: medium-volatile bituminous coal.

mylonite
 * A compact, chertlike rock without cleavage, but with a streaky or banded structure, produced by the extreme granulation and shearing of rocks that have been pulverized and rolled during overthrusting or intense dynamic metamorphism. Mylonite may also be described as a microbreccia with flow texture. See also: cataclasite; protomylonite; mylonite gneiss; ultramylonite.

mylonite gneiss
 * A mylonitic rock that has been partly recrystallized. See also: augen schist; cataclasite; flaser gabbro; mylonite; phyllonite.

mylonitization
 * Deformation of a rock by extreme microbrecciation, due to mechanical forces applied in a definite direction, without noteworthy chemical reconstitution of granulated minerals. Characteristically the mylonites thus produced have a flinty, banded, or streaked appearance, and undestroyed augen and lenses of the parent rock in a granulated matrix. Also spelled mylonization.

mylonization
 * See: mylonitization.

myrickite
 * a. A white or gray chalcedony, opal, or massive quartz unevenly colored by, or intergrown with, pink or reddish inclusions of cinnabar, the color of which tends to become brown. The opal variety is know as opalite.

b. Cinnabar intergrown with common white opal or translucent chalcedony.

myrmekite
 * An intergrowth of plagioclase feldspar (commonly oligoclase) and vermicular quartz, generally replacing potassium feldspar; formed during the later stages of consolidation in an igneous rock or during a subsequent period of plutonic activity. The quartz occurs as blobs. See: vermicular quartz.

myrmekite antiperthite
 * Myrmekitelike intergrowth of predominant plagioclase and vermicular orthoclase. The wormlike forms of orthoclase are, as a rule, broader than those of quartz in the typical myrmekite.

myrmekite perthite
 * Myrmekitelike intergrowth of microcline and vermicular plagioclase.