Appendix:Dictionary of Mining, Mineral, and Related Terms/M/5

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An epoch of the later Tertiary period, after the Oligocene and before the Pliocene; also, the corresponding worldwide series of rocks. It is considered to be a period when the Tertiary is designated as an era.


A monoclinic mineral, Na (sub 2) SO (sub 4) .10H (sub 2) O ; one perfect cleavage; tastes cool, then saline and bitter; in evaporite deposits, where it is mined as Glauber salt, and as an efflorescence. Syn: Glauber salt. (Not glauberite.)



mirror plane

See: plane of symmetry.

mirror stone

See: muscovite.

mischio marble

A violet-red breccia from Serravezza, Italy. Also known as African breccia (breche Africaine).


A natural mixture of the rare-earth metals cerium, lanthanum, and didymium; e.g., the waste matter from monazite sand after the extraction of thoria may contain large quantities of ceria, lanthana, didymia, yttria, and other substances. This is reduced to the metallic state by converting the oxides to chlorides, and then recovering the metal by electrolysis. The material obtained is an alloy containing about 50% cerium and 45% lanthanum and didymium.


A monoclinic mineral, K (sub 2) SO (sub 4) .6KHSO (sub 4) (?) ; in silky white fibers at Cape Miseno, Italy. (Not mizzonite.)


A tubular well-boring bit, having a valve at the bottom, and a screw for forcing the earth upward. Also spelled mizer.


An explosive charge in a drill hole that has partly or completely failed to explode as planned. Causes include unskilled charging; defective explosive, detonator, or fuse; broken electric circuit or--most dangerous--cutting off of part or all of the charge through lateral rock movement as other holes in the vicinity are fired. Stringent safety precautions cover procedure in minimizing these risks and in dealing with known or suspected misfires. A smoldering fuse may delay explosion, causing a hangfire, so return to workings after a suspected failure is necessary. Another main cause of accident is drilling into or dangerously near a socket--an apparently empty drill hole. See also: missed hole; hangfire.

misfire hole

See: missed hole.


See: arsenopyrite.

misplaced material

a. In mineral processing, material, particularly screen products and tailings, that has been reported in the wrong section.

b. Material wrongly included in the products of a sizing or density separation; i.e., material that has been included in the lower size or specific gravity product but which itself has a size or specific gravity above that of the cut point, or vice versa. Its weight may be expressed as a percentage of the product or of the feed. Also called tramps (undesirable usage). c. In sizing and screening, undersize contained in the overflow, or oversize contained in the underflow. d. In cleaning, material of specific gravity lower than the separation density that has been included in the high density product, or material of specific gravity higher than the separation density that has been included in the low density product.

missed hole

A drill hole charged with explosives, in which all or part of the explosive has failed to detonate. Syn: misfire; misfire hole.

missed round

A round in which all or part of the explosive has failed to detonate.


A period of the Paleozoic era (after the Devonian and before the Pennsylvanian), thought to have covered the span of time between 345 and 320 million years ago; also, the corresponding system of rocks. It is named after the Mississippi River valley, in which there are good exposures of rocks of this age. It is the approximate equivalent of the Lower Carboniferous of European usage.


An old term for copiapite and related minerals.

Mitchell system for underhand quarrying of panel cores

See: underhand stoping.

miter gear

See: bevel gear.


A monoclinic mineral, Ca (sub 2) Fe (sub 3) (PO (sub 4) ) (sub 3) O (sub 2) .3H (sub 2) O ; forms red crystals, green stains in granite pegmatites.

M.I.T. sampler

A single-tube, drive-type, soil-sampling barrel esp. adapted to sampling deposits of plastic clay where a minimum 5-in (12.7-cm) diameter sample is required. A loop or snare of piano wire is inserted in a groove inside the cutting shoe with the free end of the wire extending through a slot on the side of the sampler to the surface. When pulled, the wire cuts the sample off at the bottom of the cutting shoe.


A tetragonal mineral, K (sub 2) CuCl (sub 4) .2H (sub 2) O ; greenish blue.


See: solid solution.


Drill diamonds ranging from 23 to 80 per carat in size.

mixed blast process

A modification of the basic Bessemer process in which all the nitrogen is removed from the blast, it being made up of a mixture of oxygen and carbon dioxide or oxygen and superheated steam. The oxygen and superheated steam blast is claimed to be the more efficient, the final nitrogen content of the metal being brought to a mean level of 0.0028%.

mixed cements

A product obtained by mixing, or blending, either portland, natural, or pozzolana cement with one another or with other inert substances.

mixed crystal

See: solid solution.

mixed dust

Dust prepared for testing in a mine by mixing coal dust and inert dust in predetermined proportions. The mixture may also contain water, and different sizes of coal dust may be mixed to produce some desired intermediate size.

mixed explosion

Occurs when both combustible gases and coal dust are present below their lower limits, but in combination produce sufficient heat of combustion to propagate an explosion.

mixed explosive

Explosive consisting of an intimate mechanical mixture of substances which consume and generate oxygen but are not in themselves explosive. Inorganic nitrates, chlorates, and perchlorates. Most important is ammonium nitrate.

mixed face

In tunneling, digging in dirt and rock in the same heading at the same time.

mixed-feed kiln

Upright lime kiln in which the fuel (coal) is mixed and burned with the limestone charge.

mixed-flow fan

A mine fan in which the flow is both radial and axial. The Schicht fan is of this type and has the advantage that it can produce a high water gage with a single stage. This fan, however, is not well suited to mines where a large change in equivalent orifice may occur. CF: axial-flow fan; radial-flow fan.

mixed-flow turbine

An inward flow, reaction-type water turbine, in which the runner vanes are so shaped that they are acted on by the water pressure both axially and radially.

mixed-layer mica

a. See: clay mineral.

b. Layered silicates, generally of the smectite group, in which different layered mineral species are stacked in an ordered or random fashion.

mixed-layer mineral

A mineral whose structure consists of alternating layers of clay minerals and/or mica minerals; e.g. chlorite, made up of alternating biotite and brucite sheets.

mixed ore

Ore containing both oxidized and unoxidized minerals. See also: oxidized ore; sulfide ore.


a. An apparatus used to thoroughly mix drilling fluid water with drilling ingredients. May be cement, mud, or lost circulation materials. Also called atomizer; mud mixer.

b. See: agitator.

mixer cone

A funnel-shaped hopper attached to the body of a mud mixer into and by means of which the dry, powdered, drill-mud and/or cement ingredients are fed into the mud mixer.

mix-house person

One who mixes sintered lead or zinc ore with such materials as pulverized coal and coke, salt, skimmings, water, and chemical solutions preparatory to smelting. Also called mixer operator.


a. In powder metallurgy, the thorough intermingling of powders of two or more different materials (not blending).

b. An instrumentation technique used in seismograph recording in which a certain portion of the energy from each amplifier channel is fed to the adjacent channels, giving results somewhat analogous to those obtained from the use of multiple geophones to attenuate noise.

mixing pit

A pit in which drill mud is mixed and stored until the mud is cured and needed for use as a drill circulation fluid.


A common soil stabilization method in which the soil on the site is first pulverized, then mixed with an admixture or stabilizing agent, compacted and, if necessary, surfaced. All the work is carried out on the site. CF: plant mix.


a. A hexagonal mineral, BiCu (sub 6) (AsO (sub 4) ) (sub 3) (OH) (sub 6) .3H (sub 2) O . CF: chlorotile.

b. The mineral group agardite, goudeyite, mixite, and petersite.


Cerium alloy (55% to 65%) containing rare-earth metals and iron.


A commingling in which the ingredients retain their individual properties or separate chemical nature. See also: mechanical mixture.


One of the series of minerals forming the scapolite groups, consisting of a mixture of the meionite and mariolite molecules. It includes those minerals with 54% to 57% silica, and occurs in clear crystals in the ejected masses on Mount Somma, Vesuvius, Italy. Also called dipyrite. See also: dipyre.

MM diamond

Synthetic manufactured diamond.


a. A ditch or deep trench.

b. To surround with a ditch.


A backing of clay, as for the masonry lining of a shaft.

mobile belt

An elongated zone of the Earth's crust subjected to relatively great structural deformation. CF: geosyncline.

mobile conveyor

A hand-loaded, hoist-operated hauler used principally in certain central Pennsylvania coal mines. It is essentially a chain-and-flight conveyor of exceptional width, with high sideboards, mounted on wheels for operation on mine track, with motive power supplied by a hoist mounted on the chassis of the machine. The conveyor chain and flights can be moved in the bed of the machine to assist in loading or unloading. The hoist rope can be attached to props at the face and near the dumping point to provide anchorage when the conveyor is moved.

mobile crane

A crane driven by gasoline, diesel, or electric motor, traveling on crawler tracks, pneumatic tires or solid rubber tires, and capable of moving in any direction under its own power.

mobile drill

A drill unit mounted on wheels or crawl-type tracks to facilitate moving.

mobile equipment

Applied to all equipment that is self-propelled or that can be towed on its own wheels, tracks, or skids.See also: transportable equipment.

mobile hoist

A platform hoist which is mounted on a pair of pneumatic-tired road wheels, so that it can be towed from one site to another. This type of hoist has been developed for use in house and flat construction. See also: platform hoist.

mobile loader

A self-propelling machine capable of lifting material off the bottom and placing it in a mine car, conveyor, or other means of transportation.

Mocha stone

Syn: moss agate. Also called Mocha pebble. From Mocha, Yemen.

mock lead

A Cornish term for zinc blende; also called wild lead. See: sphalerite.

mock ore

See: sphalerite.

mock vermilion

A basic chromate of lead.


a. The mineral composition of a rock, usually expressed in weight or volume percentages. Adj: modal. CF: norm.

b. The value or group of values that occurs with the greatest frequency in a set of data; the most typical observation. CF: mean.


a. A facsimile in three dimensions--a reproduction in miniature of the surface and underground workings of a mine, showing the shafts, tunnels, crosscuts, etc., in all their details. From its very nature, it does not fall within any definition of the word map and it is a misapplication of the term to call it a map, though it may far better serve the purpose in hand.

b. A unifying concept that explains or describes a complex phenomenon. See also: mineral deposit model.

model analysis

The comprehensive testing of scale models of various structures, including harbors and rivers to determine the behavior of the actual structure under consideration. See also: photoelasticity.


a. Person who shapes plaster of Paris, clay, etc., to form original models used to make molds for producing ceramic ware.

b. Person who builds models used in model analysis.

modeling clay

Fine, plastic clay, esp. prepared for artists in modeling by kneading with glycerin, or by other methods.

moderate vitrain

A field term that, in accordance with an arbitrary scale established for use in describing banded coal, denotes a frequency of occurrence of vitrain bands comprising from 13% to 30% of the total coal layer. CF: sparse vitrain; abundant vitrain; dominant vitrain.

modified longwall

A method used in room-and-pillar mining where the lease requires at least 80% of recovery. Basically it consists of turning the rooms on 70-ft (21.3-m) centers then working the room up 30 ft (9.1 m) wide and butting it off at its completion, then withdrawing the remaining 40 ft (12.2 m) of pillar immediately.

modified room-and-pillar working

See: bord-and-pillar method.

modified-round nose

See: medium-round nose.


In froth flotation, reagent used to control alkalinity and to eliminate harmful effects of colloidal material and soluble salts. See also: modifying agent.

modifying agent

In flotation, a chemical that increases the specific attraction between collector agents and particle surfaces, or conversely, that increases the wettability of those surfaces.


A control adjusting by increments.

modulus of elasticity

The ratio of stress to its corresponding strain under given conditions of load, for materials that deform elastically, according to Hooke's law. It is one of the elastic constants. See also: modulus of rigidity; bulk modulus. Syn: elastic modulus; longitudinal velocity.

modulus of incompressibility

The ratio between the pressure in the mass of a soil and the change of volume caused by such pressure. CF: Poisson's ratio.

modulus of rigidity

a. The rate of change of unit shear stress with respect to unit shear strain, for the condition of pure shear within the proportional limit. For nonisotropic materials such as wood it is necessary to distinguish between the moduli of rigidity in different directions.

b. A modulus of elasticity in shear. Symbol: mu or G. Syn: shear modulus; rigidity modulus; coefficient of rigidity.

modulus of rupture

a. Nominal stress at fracture in a bend test or a torsion test. In bending, modulus of rupture is the bending moment at fracture divided by the section modulus. In torsion, modulus of rupture is the torque at fracture divided by the polar-section modulus.

b. The load required to break a piece of material, such as a refractory brick, supported on two spaced and parallel flat bearing edges with the load applied through a third bearing edge placed midspan and on top of the piece.

Moebius process

A method of electrolytic refining of silver. Silver plate of 95% to 98% pure forms the anodes, and thin silver plate forms the cathodes. The electrolyte consists of a weak, acidulated solution of silver nitrate.

Moe gage

A diamond-weight calculator which estimates to within a few hundredths the weights of brilliant-cut diamonds only, by simple measurements of width and depth of both set or unset diamonds.


The exhalation of carbon dioxide in an area of late-stage volcanic activity; also, the small opening from which the gas is emitted. Occurs in Yellowstone National Park. Etymol: French, noxious gas.


Monoclinic silica, SiO (sub 2) (silica-G), with quartz in chert from dry lake beds; also cavity fillings in rhyolitic ignimbrites. Named for Mogan, Canary Islands.


Titaniferous magnetite with exsolved ulvoespinel. CF: titanomagnetite.


A dull white hydrous borate of sodium, Na (sub 2) B (sub 4) O (sub 7) .5H (sub 2) O . Rhombohedral. An alteration film on borax. Locally, octahedral borax (same as tincalconite). From the Mohave Desert, CA. See also: octahedral borax.


Short name for the Mohorovicic discontinuity separating the Earth's crust from the mantle.


The never-completed program to drill through the Earth's crust under the ocean to the Mohorovicic discontinuity in order to provide scientific knowledge of the Earth's mantle.

Mohorovicic discontinuity

The boundary surface or sharp seismic-velocity discontinuity that separates the Earth's crust from the subjacent mantle. It marks the level in the Earth at which P-wave velocities change abruptly from 6.7 to 7.2 km/s (in the lower crust) to 7.6 to 8.6 km/s or average 8.1 km/s (at the top of the upper mantle); its depth ranges from about 5 km beneath the ocean floor to about 35 km below the continents, although it may reach 60 km or more under some mountain ranges. The discontinuity probably represents a chemical change from basaltic or simatic materials above to peridotitic or dunitic materials below, rather than a phase change (basalt to eclogite); however, the discontinuity should be defined by seismic velocities alone. It is variously estimated to be between 0.2 and 3 km thick. It is named in honor of its discoverer, Andrija Mohorovicic (1857-1936), Croatian seismologist. Abbrev. Moho. Syn: M-discontinuity.

Mohr balance

See: Westphal balance.

Mohr circle

A graphical representation of the stresses acting on the various planes at a given point.

Mohr-Coulomb criterion

The most popular of numerous rock failure criteria. It assumes that there is a functional relationship between the normal and shear stresses acting on a potential failure surface.

Mohr envelope

The envelope of a series of Mohr circles representing stress conditions at failure for a given material. According to Mohr's rupture hypotheses, a rupture envelope is the locus of points, the coordinates of which represent the combination of normal and shearing stresses that will cause a given material to fail. Syn: rupture envelope; rupture line.

Mohr's salt

A ferrous-ammonium sulfate, FeSO (sub 4) (NH (sub 4) ) (sub 2) SO (sub 4) .6H (sub 2) O ; a light green crystalline salt.

Mohr's theory

Mohr's theory of failure utilizes the well-known stress circle and the envelope of a family of circles as criteria for failure of materials subject to biaxial or triaxial stress. Thus Mohr's theory predicts that failure of materials is due to failure in shear, whereas Griffith's theory postulates that it is due to failure at crack tips.


A plumboan variety of crichtonite.

Mohs scale

Arbitrary quantitative units by means of which the scratch hardness of a mineral is determined. The nonlinear units of hardness are expressed in numbers ranging from 1 through 10, each of which is represented by a mineral that can be made to scratch any other mineral having a lower-ranking number; hence the minerals are ranked from the softest, as follows: talc (1) ranging upward in hardness through gypsum (2), calcite (3), fluorite (4), apatite (5), orthoclase (6), quartz (7), topaz (8), corundum (9), to the hardest, diamond. CF: hardness; Knoop hardness.

moil point

A solid bar of casehardened steel, pointed at one end, with a shank and upset collar at the other. The moil point, hammered into rock or concrete, produces a small hole that gradually deepens and widens until the sides of the point are in full contact with the rock. The effect is then that of wedging, similar to plug-and-feathering.


A hexagonal mineral, alpha-SiC (Carborundum); in meteorites. See also: Carborundum.

Moissan process

A process for the reduction of chromic oxide with carbon in an electric furnace, the hearth of which is lined with a calcium chromite prepared by heating together lime and chromic oxide.


a. Agreed percentage of water content to be allowed in mineral products that are sold.

b. Essentially water, quantitatively determined by definite prescribed methods which may vary according to the nature of the material.

moisture allowance

A deduction from the inital weight of washed coal to allow for the expected loss of water by drainage.

moisture content

The percentage moisture content equals the weight of moisture divided by the weight of dry soil multiplied by 100. The moisture content of a coal or mineral sample consists of two portions, namely, the free or surface moisture which can be removed by exposure to air, and the inherent moisture which is entrapped in the fuel, and is removed by heating at 200 degrees F (93.3 degrees C). Syn: inherent moisture; water content.

moisture-density curve

See: compaction curve.

moisture-density test

See: compaction test.

moisture equivalent

The ratio of the weight of water--which soil, after saturation, will retain against a centrifugal force 1,000 times the force of gravity--to the weight of the soil when dry. The ratio is stated as a percentage.

moisture-holding capacity

The quantity of moisture (not removable by mechanical means) contained by a coal in equilibrium with an atmosphere saturated with water vapor. This is employed in some systems of classification as a criterion of rank.

moisture man

Person who determines the moisture content of ores or concentrates by removing a sample from pile or conveyor, using a metal paddle, and weighing the sample before and after drying.

moisture meter

An instrument for determining the percentage of moisture in a substance such as timber or soil, usually by measuring its electrical resistivity. See also: atomic moisture meter.

moisture sample

A sample taken for the determination of moisture content.


See: tincalconite.


a. A partly marine, partly continental sedimentary facies consisting of a thick sequence of fossiliferous conglomerates, sandstones, shales, and marls, characterized by primary sedimentary structures and sometimes by coal and carbonate deposits. It is more clastic and less rhythmic than the preceding flysch facies.

b. An extensive sedimentary formation representing the totality of the molasse facies resulting from the wearing down of elevated mountain ranges during and immediately after the main paroxysmal (diastrophic) phase of an orogeny, and deposited considerably in front of the preceding flysch. Adj: molassic. CF: flysch.

molasses/AN explosive

An explosive mixture consisting of about 80 lb (36.5 kg) of ammonium nitrate mixed with 10 pints (4.7 L) of molasses and 5 pints (2.37 L) of water, for quarry and opencast blasting. The molasses and water may be used instead of fuel oil and give a denser mixture with improved fragmentation.


A body of molding sand or other heat-resisting material containing a cavity which when filled with molten metal yields a casting of the desired shape. See also: die. CF: cast.


a. A tektite from the Moldau valley, Czech Republic. Syn: glass meteorite.

b. A variety of ozocerite from Moldavia. See also: bouteillenstein.


a. A board on which to ram a pattern.

b. A curved surface of a plow, dozer, or grader blade, or other dirt mover, which gives dirt moving over it a rotary, spiral, or twisting movement.

molded cameo

A cameo produced by casting in a mold material such as ceramics, metals, glass, plastics, or sealing wax. CF: pressed cameo.


An obsolete term for decomposition of organic matter under conditions of insufficient oxygen.

molders' rule

A ruler, with measurements sufficiently elongated to compensate for the heat expansion and contraction of a metal. Such rules are used in metal casting to correct dimensions to normal temperatures.


a. The practice of pouring molten metal into suitable molds.

b. The pressing of powder to form a compact.

molding compound

A mixture of resins, ingredients, and fillers before processing into the finished product.

molding frame

A template to shape a loam mold.

molding hole

An excavation in a foundry floor for large castings.


Derb. Weathered ore at the surface of an outcrop.

mold plug

A truncated-cone-shaped refractory piece which sits in the bottom of an ingot mold.


a. A massive, solid-fill nearshore structure of earth, masonry, or large stone that may serve as either a breakwater or a pier.

b. An egg-shaped device pulled behind the tooth of a subsoil plow to open drainage passages. Also called mole ball. c. Weight in grams of a compound in terms of its molecular weight.

molecular crystal

Loosely bound aggregate of stable molecules; e.g., dry ice, solid iodine, sulfur, paraffin, and most of the other crystalline organic solids.

molecular filter sampler

Using a porous membrane filter of very small openings, this sampler achieves nearly 100% efficiency at moderate rates of flow. Membranes of three different porosities are used to permit the sampling of dusts of varying concentrations and particle sizes. Flow rate is controlled by the use of calibrated orifices. Syn: membrane filter.

molecular sieve

A microporous structure of either crystalline aluminosilicates, such as zeolites, or crystalline aluminophosphates, created by dehydration so that the empty cavities in the structure where water molecules were previously present will accept any material that can penetrate the cavity. The sieving action is a function of the pore size of the structure.


a. The smallest part of a substance that can exist separately and still retain its composition and characteristic properties.

b. The smallest combination of atoms that will form a given chemical compound.

mole mining

A method of working coal seams about 30 in (76.2 cm) thick, using a small continuous miner type of machine, which is remotely controlled from the roadway and without any associated supports. The machine is used to cut and extract sections of coal about 6 ft (1.8 m) wide for a distance of 100 yd (91 m) or so from pillars alongside the roadway. Small ribs of coal, 3 to 6 ft (approx. 1 to 2 m) wide, are left between the sections extracted by the machine. The accurate steering of the machine is a critical feature of this system of mining. See also: coal auger.


See: lamprophyllite.


A deposit of diatomite of marine origin occurring on the island of Mors, Denmark. It has been worked since 1912 for use as a heat insulating material, as a constituent of special cements, and for other purposes.

molten slag

A waste product of smelting; usually a mixture of silicates.


An amorphous mineral, H (sub 4) U(UO (sub 2) ) (sub 3) (MoO (sub 4) ) (sub 7) .18H (sub 2) O .


A hexagonal and trigonal mineral, MoS (sub 2) ; polymorphous with jordisite; foliated; soft; metallic lead gray; an accessory in granites and deep veins; an ore of molybdenum.


A silvery-white, very hard, metallic element. Symbol, Mo. Does not occur native, but is obtained principally from molybdenite. Wulfenite (PbMoO (sub 4) ), and powellite (Ca(MoW)O (sub 4) ) are also minor commercial ores. Valuable as an alloying agent with steel and nickel. Used for electrodes in electrically heated glass furnaces, in nuclear energy applications, and for missile and aircraft parts.

molybdenum aluminide

Mo (sub 3) Al; melting point, 2,150 degrees C. Although its oxidation resistance is poor compared to other aluminides and silicides, it is good compared to molybdenum metal. It is a refractory crucible material for melting certain metals.

molybdenum anhydride

See: molybdenum trioxide.

molybdenum borides

Five compounds have been reported: Mo (sub 2) B , melting point, 2,120 degrees C, and sp gr, 9.3; Mo (sub 3) B (sub 2) , dissociates at 2,250 degrees C; MoB, exists in two crystalline forms: alpha MoB, melting point, 2,350 degrees C, sp gr, 8.8; and beta MoB, melting point, 2,180 degrees C, sp gr, 8.4; Mo (sub 2) B (sub 5) , dissociates at approx. 1,600 degrees C, sp gr, 7.5; and MoB (sub 2) , melting point, 2,100 degrees C, sp gr, 7.8, and thermal expansion, 7.7 x 10 (super -6) .

molybdenum carbides

MoC, melting point 2,692 degrees C, sp gr, 8.5; Mo (sub 2) C , melting point 2,687 degrees C, sp gr, 8.9.

molybdenum disilicide

MoSi (sub 2) ; gray; metallic; tetragonal; and melting point, 2,000 degrees C. It has good oxidation resistance at elevated temperatures; maintains fairly good strength; and has refractory applications. Molecular weight, 152.11; sp gr, 6.31 (at 20.5 degrees C); insoluble in acids and in aqua regia; and soluble in hydrofluoric acid plus nitric acid. Syn: molybdenum silicide.

molybdenum mineral

Most molybdenum is a byproduct of mining porphyry copper deposits.

molybdenum silicide

See: molybdenum disilicide.

molybdenum trioxide

MoO (sub 3) ; white at ordinary temperatures; yellow at elevated temperatures; molecular weight, 143.94; orthorhombic; sp gr, 4.69 (at 21 degrees C); melting point, 795 degrees C; boiling point, 1,264 degrees C or sublimes at 1,155 degrees C, at 1 atmophere (101 kPa); sparingly soluble in water; very soluble in excess alkali with the formation of molybdates; and soluble in concentrated mixtures of nitric and hydrochloric acids and in mixtures of nitric and sulfuric acids.

molybdic ocher

See: ferrimolybdite.

molybdic oxide

See: molybdenum trioxide.


See: ferrimolybdite; molybdenum trioxide.


A monoclinic mineral, PbSeO (sub 3) .


A trigonal mineral, Pb (sub 2) Mg (sub 2) Si (sub 2) O (sub 7) (OH) (sub 2) .

moment distribution

A method of calculating bending moments, in redundant frames and continuous beams, using successive approximations.

moment of force

The turning effect on a body about a point called a pivot or fulcrum. In practice, the turning effect is commonly called leverage. Syn: turning effect.

moment of inertia

Resistance by a body to angular acceleration about a specific axis of rotation.

moment of resistance

The couple produced by the internal forces in a beam subjected to bending under the maximum permissible stress.


Mass times velocity.

momentum grade

Grade so situated that the kinetic energy of a train (due to its speed at the foot of the grade) will enable the locomotive to haul the train to the top without a reduction of speed below 10 or 12 mph (16.1 to 19.3 km/h).

Momertz-Lintz system

A unique winding arrangement where two winding engines are arranged alongside the shaft, the shaft collar forming a common foundation. The ropes are practically vertical and there is less rope oscillation.

M.O. Mine safety indicator

A system showing, by means of lights, the position of all switchgear underground, with a master control that would show up if a section of a mine had been switched off at the substation, leaving switches going into the mine in the on position. A recorder gives a complete operating picture of a power-loading face.


An axial rotation of 360 degrees , one-fold. See also: axis of symmetry.


A residual hill rising above a peneplain, representing an isolated remnant of a former erosion surface. It is named after Mt. Monadnock, NH. CF: inselberg.


a. A monoclinic mineral, (Ce,La,Y,Th)PO (sub 4) ; waxy yellow to brown; an accessory in granites; pegmatites, and placers; a source of thorium and rare earths; further speciated according to the dominant rare-earth element. See also: zircon group.

b. The mineral group brabandite, cheralite, huttonite, monazite, and rooseveltite.

monazite sand

See: monazite.


A trigonal mineral, (Te,Bi) (sub 2) ; melonite group; steel-gray; in chalcopyrite on the Kola Peninsula, Russia.


A lamprophyre containing phenocrysts of olivine, clinopyroxene, and typically biotite or amphibole (barkevikite), in a groundmass of glass or analcime, often highly altered. Nepheline or leucite may be present. Its name is derived from Serra de Monchique, Portugal.

Mond process

A process for extracting and purifying nickel. The main features consist of forming nickel carbonyl by reaction of the finely divided reduced metal with carbon monoxide, and decomposing the nickel carbonyl, with deposition of nickel on small nickel pellets.


A triclinic mineral, CaHPO (sub 4) ; yellowish-white; in phosphorites.


Eng. Irregular gray limestone, Lower Lias, Lyme Regis.


A variety of smithsonite containing iron carbonate.


a. A high-pressure nozzle, mounted in a swivel on a skid frame, used to direct high-pressure water (hydraulic water) on unconsolidated gravels and sands in alluvial mining to break down, wash, and transport them. Syn: hydraulic monitor.

b. A self-dumping car, holding from 5 to 8 tons of coal. It is filled by emptying the mine car into it at the foot of the slope or top of the incline. See also: gunboat. c. A gas sampler for continuous sampling of the atmosphere in a mine, usually sounding an alarm when the gas threshold is exceeded. d. An instrument that measures ambient conditions in an area. e. In hydraulicking, a high-pressure nozzle mounted in a swivel on a skid frame.

monitor operator

See: incline man.


a. The word monkey prefixed to a technical term means small, thus: monkey chute, a small chute; monkey drift, a small drift, usually driven in for prospecting purposes.

b. An appliance for mechanically gripping or letting go the rope in rope haulage. c. A block placed between the rails on an incline to prevent cars from running back. Syn: monkey chock; bobbin.

monkey board

A single, unrailed, heavy plank, mounted above the drill platform in the derrick or tripod and serving as a walkway or work platform.

monkey chock

Aust. See: monkey; bobbin.

monkey drift

A small drift driven in for prospecting purposes, or a cross-cut driven to an airway above the gangway.

monkey face

A term applied to a chain bracket to be inserted between adjacent shaker conveyor troughs to permit suspension of the trough line from the roof.

monkey gangway

a. Pennsylvania. An air course driven parallel with a gangway and heading at a higher level. Used where a seam has considerable pitch or dip.

b. A small gangway parallel to a main gangway.

monkey hair

Caotchouc, or rubber, derived from a milk juice of plants and which fills latex cells and tubes. It is resistant to decomposition and found in many brown coals as a wooly mass.

monkey heading

A narrow and low passage driven in the coal where miners take refuge while coal is being blasted. Chiefly in mines where seams pitch sharply.

monkey hole

See: doghole.

monkey roll

Any of the smaller rolls in an anthracite breaker.

monkey shaft

A small shaft raise extending from a lower to a higher level.

monkey winch

A device for exerting a strong pull; may be used to withdraw steel arches from disused roadways. It consists of a framework containing a hand-operated drum, around which a steel rope 50 ft (15.24 m) in length is wound. To hold the drum in position a ratchet device is used with both gears. A simple reversing mechanism that disengages the ratchet is also attached. The winch is firmly anchored when in use. See also: winch; sylvester.

monkey wrench

An adjustable wrench named for its inventor, Thomas Monkey.

Monnier process

The treatment of copper sulfide ores by roasting with sodium sulfate, and subsequent lixiviation and precipitation.


Containing one hydrogen atom replaceable by a metal with the formation of a salt.


A form of aerial ropeway in which the same rope is used both to support and haul along the overturning skips in which the debris is carried. These rest upon the rope and obtain a sufficient frictional grip on it to be carried up moderate gradients and over pulleys by means of an inverted Vee-shaped saddle lined with wood, rubber, or composition. The rope is driven by a surge wheel in a similar manner to an endless-rope haulage. See also: aerial ropeway; fixed-clip monocable.


Having or consisting only of one color or frequency.

monochromatic light

Electromagnetic radiation of a single wavelength or frequency.


Adj. of monocline.


A local steepening in an otherwise uniform gentle dip. CF: anticlinal bend; homocline; flexure. Adj: monoclinal. Obsolete syn: unicline.

monoclinic block

A quarryman's term for blocks with two parallel sets of sides at right angles and one parallel set not at right angles.

monoclinic system

All point groups characterized by lattices with two crystallographic axes at right angles and one axis inclined. See also: crystal systems.


a. See: monogenetic.

b. Said of an igneous rock (such as dunite) composed essentially of a single mineral. Syn: monomineralic.


a. Resulting from one process of formation or derived from one source, or originating or developing at one place and time; e.g., said of a volcano built up by a single eruption.

b. Consisting of one element or type of material, or having a homogeneous composition; e.g., said of a gravel composed of a single type of rock. CF: polygenetic. Syn: monogene.


A free-flowing high explosive widely used for charging bulled holes and large-diameter (well drill) holes.


a. A piece of unfractured bedrock, generally more than a few meters across; e.g., an unweathered joint block moved by a glacier.

b. A large upstanding mass of rock, such as a volcanic spine. c. One of many large blocks of stone or concrete forming the component parts of an engineering structure, such as a dam. d. A vertical soil section, taken to illustrate the soil profile.

monolithic refractory

Furnace lining made in one piece or formed by casting, ramming, or tamping into position.


Coal microlithotype consisting of a single maceral; i.e., fusite or vitrite.


See: monogene.


Upper Pennsylvanian geologic time.

Monongahela series

The Upper Productive Coal Measures of the Pennsylvanian, of which they constitute the highest member.

Mono pump

This pump consists essentially of a rubber stator in the form of a double internal helix and a single helical rotor which rolls in the stator with a slightly eccentric motion. The rotor maintains a constant seal across the stator and this seal travels continuously through the pump, giving a positive uniform displacement. The Mono pump is manufactured to meet mining conditions. The rotor is made of special abrasion-resisting or noncorroding steel. The length of the stator and rotor provides for a twist of slightly more than 360 degrees to provide for a complete seal. For greater heads the length of stator and rotor are increased so as to provide two or more complete seals in series and the head is then developed in stages. Syn: progressing cavity pump.


See: clinopyroxene.


A relatively new underground transport system in which the carriages, or buckets, are suspended from, and run along, a single continuous overhead rail or taut wire rope. The monorail is used in coal mines to transport supplies to the workings. It may be installed alongside the gate conveyor and worked by endless or main rope. See also: overhead monorail; overhead-rope monorail; Becorit system.

monorail crane

A traveling crane suspended from a single rail.


Said of a body of rock or a mineral deposit, the fabric of which is identical throughout.

monotower crane

A tower crane that rotates through a full circle and is erected on a fixed base.


An indentation hardness testing machine by which measurements are obtained by the pressure required to indent a specimen with a diamond 5/8 mm in diameter, the depth of indentation remaining constant.

monotron hardness test

A method of determining the indentation hardness of metals by measuring the load required to force a spherical penetrator into the metal to a specified depth.


a. Having a valence of 1.

b. Having one valence; e.g., calcium, which has only one valence of 2.


a. Sp. Mountain.

b. Mex. Ores scattered through country rock and not found in deposits of any appreciable size.

Montana agate

Moss agate from Montana.

Montana ruby

Red garnet, pyrope or almandine.

Montana sapphire

Electric or steel-blue sapphire from Montana.


A possibly monoclinic mineral, Be (sub 2) TeO (sub 6) .2H (sub 2) O ; yellow to white; forms earthy encrustations.

montan wax

brown coals. It is white to brown and melts at 77 to 93 degrees C.


A variety of amosite; an asbestiform variety of amphibole.

Mont Blanc ruby

Rose quartz from Mont Blanc, southeastern France.


A triclinic mineral, (Au,Sb) (sub 2) Te (sub 3) ; forms tin-white crystals at Montbray, Quebec. Named for the locality.


A triclinic mineral, LiAl(PO (sub 4) )(OH (sub 1) F) ; amblygonite group; perfect cleavage; occurs in granite pegmatites where it may be a source of lithium.

Montgomery jig

A plunger-type jig with the plunger beneath the screen. The distinguishing feature of this jig is the use of two sets of valves beneath the screen plate. Used in washing bituminous coal, both closely sized and slack sizes.


European stage: Paleocene (above Danian, below Thanetian).


An orthorhombic mineral, MgCaSiO (sub 4) ; olivine group; in contact-metamorphosed limestones, rarely in ultramafic rocks. CF: glaucochroite.


A small hill, knob, or mound; esp., a minor volcanic cone.


Mountainlike; having the shape of a mountain.


A monoclinic mineral, (Na,Ca) (sub 0.33) (Al,Mg) (sub 2) Si (sub 4) O (sub 10) (OH) (sub 2) .nH (sub 2) O ; smectite group; expansive and cation exchangeable; perfect basal cleavage; in bentonite clays formed by alteration of volcanic ash or mafic igneous rocks. The chief constituent of bentonite and fuller's earth. CF: beidellite; hectorite. Syn: amargosite.


An opening in a kiln wall to permit inspection of the contents.


An orthorhombic mineral, (V,Fe)O(OH) ; black; a primary mineral in sandstone-type uranium-vanadium ores associated with roscoelite, pitchblende, coffinite, and secondary uranium and vanadium minerals.


An orthorhombic mnineral, HgO ; sectile; perfect cleavage; sp gr, 11.2; a rare secondary mineral; in the oxidized zone of some mercury deposits.


a. The structure erected to mark the position of a corner. Permanence is implied. In a legal sense, a monument is any physical evidence of a boundary of real property.

b. Survey point; e.g., a pile of stones indicating the boundary of a mining claim.


A granular plutonic rock containing approx. equal amounts of orthoclase and plagioclase, and thus intermediate between syenite and diorite. Quartz is minor or absent. Either hornblende or diopside, or both, are present and biotite is a common constituent. Accessories are apatite, zircon, sphene, and opaque oxides. The intrusive equivalent of latite. Syn: syenodiorite.


A tetragonal mineral, Cu (sub 9) Fe (sub 9) S (sub 16) ; in magmatic sulfide deposits; a significant copper ore mineral at Noril'sk, Russia.


a. A semitransparent to translucent variety of alkali feldspar (adularia) or cryptoperthite that exhibits a bluish to milky-white pearly or opaline luster; an opalescent variety of orthoclase; a gemstone if flawless. CF: sunstone. Syn: hecatolite. See also: feldspar.

b. A name incorrectly applied to peristerite or to opalescent varieties of plagioclase (esp. albite). c. A name incorrectly applied (without proper prefix) to milky or girasol varieties of chalcedony, scapolite, corundum, and other minerals.

moonstone glass

A type of opal glass resembling the mineral moonstone.


a. A more or less elevated tract of barren land, having, as a rule, a rather broad, flat, and poorly drained surface, commonly diversified by peat bogs and patches of heath.

b. A common term for peat unfit for use, as opposed to turf, which is dug for fuel.


See: moorband pan.

moorband pan

Eng. A hard ferruginous crust that forms at the bottom of boggy places above a stiff and impervious subsoil.

Moore and Neill sampler

A sediment coring device containing a protected glass tube through which water flows freely during descent and which is forced by impact into the sediment. On hauling, a simple valve mechanism closes the top of the tube and the sample may be brought to the surface. The body of the sampler is a brass cylinder into which fits a thinner metal tube holding the glass sampling tube. When the glass tube is in position, it is closed by a rubber bung that comes hard against the upper surface of the main body of the sampler in the center of which is a hole.

Moore filter press

A movable, intermittent vacuum filter consisting of a series, or basket, of leaves fastened together in such a way that it may be dropped in a pulp tank and kept submerged until a cake is formed; it is then transferred by crane to an adjoining wash-solution tank and washed; the basket is then lifted out of the tank and the cake dropped.

Moore free corer

A sediment sampler designed to drop free from a ship to the sea floor, obtain a core, and return to the surface, leaving its expendable weight and casing embedded in the bottom. The free corer consists of two basic assemblies: (1) a recoverable core barrel, check valve, buoyant chamber assembly filled with gasoline; and (2) an expendable weight and casing assembly. When these two assemblies are combined, the core barrel fits loosely inside the casing. The device is dropped over the side of the ship and allowed to fall free to the bottom. A simple release-delay timer made of magnesium releases the core barrel and its buoyant float rises from the weight and casing assembly.

moorland peat

See: highmoor peat.


a. Remains of a submerged forest, composed of a tangled mass of brushwood and tree trunks and forming a layer from 3 to 8 ft (0.9 to 2.4 m) thick.

b. Hard, brown peat dredged by fishing boats from the bed of the North Sea.

moor peat

See: highmoor peat.

moose pasture

Can. Derisive term applied to mining country that is largely muskeg.


In contrast to "mull", a type of forest soil in which the humus layer forms a dense carpet over the soil. Synonymous with raw humus.

morainal apron

See: apron.


A mound, ridge, or other distinct accumulation of unsorted, unstratified glacial drift, predominantly till, deposited chiefly by direct action of glacier ice, in a variety of topographic landforms that are independent of control by the surface on which the drift lies. See also: boulder clay; till.

Moran and Proctor sampler

A simple, split-tube, drive-type soil-sampling barrel. The sampler is equipped with a thin-walled unsplit brass liner, which can be capped and sealed to act as a watertight shipping container for the sample.

morass ore

See: bog iron; bog iron ore.


A semigelatinous permitted explosive possessing both high power and good water-resisting properties. It has a density about midway between Dynobel No. 2 and Ajax.


A substance used in dyeing to fix the coloring matter, as a metallic compound that combines with a organic dye to form an insoluble colored compound, or lake, in the fiber of a fabric.


A white, yellowish, or pinkish member of the zeolite group of minerals with the formula (Ca,Na (sub 2) K (sub 2) )Al (sub 2) Si (sub 10) O (sub 24) .7H (sub 2) O .


An orthorhombic mineral, NiSO (sub 4) .7H (sub 2) O ; may contain appreciable magnesium; apple-green; in secondary incrustations from the oxidation of nickel-bearing sulfides. Syn: nickel vitriol.


A rose-colored, alkali-bearing, gem-quality variety of beryl identical with vorobievite. Syn: vorobievite.


The South African measure of land, equal to 640.25 square rods, 92,196 ft (super 2) (8,565 m (super 2) ), 1.44 claims, or 2.1165 English acres (0.857 ha). There are 284 morgens to a square mile and 735.5 morgens/km (super 2) .

Morisette expansion reamer

A reaming device equipped with three tapered lugs or cutters designed so that the drilling pressure necessary to penetrate rock with a noncoring pilot bit forces the diamond-faced cutters of the reamer to expand outward, thereby enlarging the pilot hole sufficiently to allow the casing to follow the reamer as drilling progresses. The casing is rotated with a pipe wrench while the noncoring and expansion bit is turned by the drill, and the casing is allowed to follow down the reamed-out pilot hole about 1-1/2 to 2 in (4 to 5 cm) behind the upper end of the reamer lugs.

Morkill's formula

Valuation formula used to ascertain present value (Vp) of a mining share.


A mottled variety of jasper found in New South Wales, Australia; much sought by miners, it commonly occurs with diamonds.

morphological crystallography

The study of the external shapes of crystals.

morphologic unit

a. A rock stratigraphic unit identified by its topographic features; e.g., a Pleistocene glacial deposit.

b. A surface, either depositional or erosional, recognized by its topographic character.


a. The observation of the form of lands.

b. The study of the form and structure of organisms. c. The form or shape of a crystal or mineral aggregate. Adj. morphological.


a. The receptacle beneath the stamps in a stamp mill, in which the dies are placed, and into which the rock is fed to be crushed.

b. A vessel in which rock is crushed by hand with a pestle for sampling or assaying.

mortar bed

Lime-cemented, valley-flat deposit of clay, silt, sand, and gravel, found in Nebraska and Kansas; a type of caliche.

mortar box

The large, deep, cast-iron box into which the stamps fall and the ore is fed in a gold or silver stamp mill; also called stamper box.

mortar structure

A structure in crystalline rocks characterized by an aggregate of small grains of quartz and feldspar occupying the interstices between, or forming borders on the edges of, much larger, rounded grains of the same minerals. Long considered a product of cataclasis, the structure may actually be the result of plastic deformation and dynamic recrystallization (Harte, 1977). Syn: porphyroclastic structure. See also: cataclastic.


See: mortise.


Destruction of active qualities, as in mercury amalgamation.


A rectangular hole cut in one member of a framework to receive a corresponding projection on the mating member. Syn: mortice.

morts terrains

a. Fr. Barren or dead ground.

b. The water-bearing strata overlying the Coal Measures.


a. An assembly of aerial or space photographs or images whose edges have been feathered and matched to form a continuous photographic representation of a part of the Earth's surface; e.g., a composite photograph formed by joining together parts of several overlapping vertical photographs of adjoining areas of the Earth's surface. See also: controlled mosaic. Syn: aerial photomosaic.

b. A textural subtype in which individual mineral grains are approx. equal (Harte, 1977).

mosaic silver

An amalgam of mercury, tin, and bismuth, used for imitating silverwork.

mosaic structure

Slight irregularity of orientation of small, angular, and granular regions of varying sizes in a crystal.

mosaic texture

a. A granoblastic texture in a dynamically metamorphosed rock in which the individual grains meet with straight or only slightly curved, but not interlocking or sutured, boundaries.

b. A texture in a crystalline sedimentary rock characterized by more or less regular grain-boundary contacts; e.g., a texture in a dolomite in which the mineral dolomite forms rhombs of uniform size so that in section contiguous crystals appear to dovetail, or a texture in a orthoquartzite in which secondary quartz is deposited in optical continuity on detrital grains.


An isometric mineral, Ag (sub 2) Hg (sub 3) ; a silver-white amalgam; sp gr, 13.5. (super ) Named for the locality in Bavaria, Germany.


An isometric mineral, Hg (sub 2) N(Cl,SO (sub 4) ,MoO (sub 4) ,CO (sub 3) ).H (sub 2) O ; yellow; secondary. See also: kleinite.


a. adj. A fine dendritic growth having the texture of moss; e.g., moss gold.

b. A term used for fractures or fissures in gem stones which produce the appearance of moss, such as in many emeralds.

moss agate

A general term for any translucent chalcedony containing inclusions of any color arranged in dendritic patterns resembling trees, ferns, leaves, moss, and similar vegetation; specif. an agate containing brown, black, or green mosslike markings due to visible inclusions of oxides of manganese and iron. See also: agate; Mocha stone; tree agate. Syn: landscape agate; medfordite.

Mossfield loader

A scraper-box type of coal loader developed at the Mossfield colliery (Great Britain) in 1953. It consists of a hinged front, scooplike plate which elevates and deflects the broken coal onto an armored conveyor. On inclined faces, the loader is hauled by a double-drum Pikrose haulage.

moss form

A material in dendritic forms.


During low water in the Salmon River, CA, the algae and other plants growing in the stream are gathered, dried, and burned. The ashes are washed, and some gold is obtained. This process is called mossing.


A tantalum-bearing variety of ferrocolumbite or tapiolite named for the locality in Norway.

moss peat

Peat derived from water-loving mosses, chiefly sphagnum. See also: highmoor peat.

mossy zinc

Granulated zinc obtained when the molten metal is poured into cold water.


a. Gouge clay in a mineral vein.

b. Shale adhering to quarried limestone. c. See: mother crystal.

mother conveyor

A term frequently used in connection with conveyors used in gathering service. The mother conveyor receives coal from other conveyors or gathering machines, such as shuttle cars, and delivers it to some central loading point. See also: underground mine conveyor.

mother crystal

A name given to a mass of raw quartz, either faced or rough, as found in nature. Syn: mother.

mother gate

a. N. of Eng. The main roadway to a coal face up which miners travel; air, power, and supplies pass; and down which coal from the face travels on a conveyor belt.

b. Eng. The main road of a district off which crossheadings are set away in longwall working. See also: level; main gate.

Mother Hubbard bit

A heavy drag-type or fishtaillike bit having a long grooved shank, the diameter of which is only slightly less than the width of the cutting edges; it is designed for drilling boreholes in formations that mud-up excessively.

mother liquor

a. The magmatic rest solution from which a mineral deposit has received its metal content.

b. In crystallization, the liquid that remains after the substances readily and regularly crystallizing have been removed.

mother lode

a. A main mineralized unit that may not be economically valuable in itself but to which workable veins are related; e.g., the Mother Lode of California. CF: master lode.

b. An ore deposit from which a placer is derived; the mother rock of a placer.

mother of coal

See: fusain; mineral charcoal.


See: prase.


Iridescent portion of mollusk shells, made of the mineral aragonite. See also: nacre.

mother rock

A general term for the rock in which a secondary or transported ore deposit originated; mother lode.

motion driver

In bituminous coal mining, one who operates the engine that moves an endless cable by which cars are raised or lowered along an inclined haulageway. Syn: motioner.


See: motion driver.

motion study

A technical investigation of the essential movements of a worker when performing a specific task, and assessing the results with the objective of reducing labor and increasing work performance. The study may also include the layout tasks, availability of tools or materials, and the design of new methods. See also: time study.

motive column

The height of a column of air, of the same density as the air in the downcast shaft, which exerts a pressure equal to the ventilating pressure. It is the ventilating pressure expressed in meters of air column. Also called head. Syn: column; ventilating column.

motive power

An agency (such as water, steam, wind, or electricity) used to impart motion to machinery.

motive zone

In mine subsidence, that portion of the mined strata which, being still in the process of sinking, goes far to furnish the motive power producing the phenomena.


A speed counter, as for a steam engine; also a speedometer.

motor body

The boxlike portion at the lower end of a coal-cutting machine.

motor boss

In mining, a foreperson who directs locomotive (motor) haulage operations underground and at the surface of a mine. Also called car dispatcher; car distributor; dispatcher; passing boss; traffic man; train dispatcher. Syn: turn keeper.

motor brakeperson

See: locomotive brakeman.

motor-change man

In anthracite and bituminous coal mining, a person who in addition to charging and repairing batteries, removes spent storage batteries from electric mine locomotives and replaces them with freshly charged ones.

motor driver

In bituminous coal mining, one who operates a small electric haulage locomotive to haul mine cars underground and at the surface of a mine.

motor hammer drill

Usually has a built-in gasoline engine as prime mover, flushing being provided by the exhaust gases or by compressed air produced in the machine. Total weight varies between 50 lb and 120 lb (22.7 kg and 54.4 kg). Motor hammer drills are used for odd-job operations, on forest roads, in prospecting, etc., where it is not worthwhile to lay air supply lines on account of transport difficulties or insufficient volume of work.

motorized grader

See: grader.


The person who operates a haulage locomotive.

motor nipper

See: locomotive brakeman.


The spotted, blotched, or variegated appearance of any mottled surface, such as of wood or marble; esp., in metallurgy, the appearance of pig iron of a quality between white and gray.

mottled iron

Pig iron in which the majority of the carbon is combined with iron in the form of cementite, Fe (sub 3) C , but in which there is also a small amount of graphite. The fractured pig has a white crystalline fracture with clusters of dark spots, indicating the presence of graphite. See also: gray iron.

mottled limestone

Limestone with narrow branching fucoidallike, cylindrical masses of dolomite, often with a central tube or hole; a variegated limestone. It may be organic or inorganic in origin.

mottled silica brick

A silica brick having harmless areas of dark cream to reddish brown.

mottled slate

Slate in which blotches of red or purplish colors appear on a generally green surface; ascribed chiefly to different forms of iron oxide.

mottled structure

Discontinuous lumps, tubes, pods, and pockets of a sediment, randomly enclosed in a matrix of contrasting textures, and usually formed by the filling of animal borings and burrows).


An orthorhombic mineral, PbCu(VO (sub 4) )(OH) ; descloizite group; zinc replaces copper toward descloizite; conchoidal fracture; a supergene mineral associated with base-metal deposits. Formerly called cuprodescloizite, psittacinite.

mountain brown ore

Limonite or brown iron ore. A local name applied in Virginia to the low-grade siliceous variety, which commonly occurs in hard lumps and is found on the mountain slopes at or near the contact of the Cambrian shale and sandstone with the Cambro-Ordovician limestone. CF: valley brown ore.

mountain building

See: orogeny.

mountain chain

A complex, connected series of several more or less parallel mountain ranges and mountain systems grouped together without regard to similarity of form, structure, and origin, but having a general longitudinal arrangement or well-defined trend; e.g., the Mediterranean mountain chain of southern Europe. See also: cordillera. CF: mountain system.

mountain cork

a. A white or gray variety of asbestos consisting of thick interlaced fibers and resembling cork in texture and lightness (it floats on water). Syn: rock cork; mountain leather.

b. A fibrous clay mineral such as sepiolite or palygorskite.

mountain flax

A fine silky asbestos.


A monoclinic mineral, (Ca,Na (sub 2) ,K (sub 2) ) (sub 2) Si (sub 4) O (sub 10) .3H (sub 2) O ; zeolitelike; white; fibrous. See also: rhodesite.

mountain leather

a. A tough variety of asbestos occurring in thin flexible sheets made of interlaced fibers. Syn: rock leather; mountain cork; mountain paper.

b. A fibrous clay mineral such as sepiolite or palygorskite. Syn: leatherstone.

mountain meal

See: diatomite.

mountain milk

A very soft, spongy variety of calcite.

mountain paper

A paperlike variety of asbestos occurring in thin sheets; specif. mountain leather or mountain cork.

mountain pediment

A plain of combined erosion and transportation at the foot of a desert mountain range, similar in form to an alluvial plain but beveling solid rock.

mountain railway

A railway having such steep gradients that trains are hauled up them by ropes or by a rack locomotive. See also: funicular railway.

mountain range

A single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain.

mountain soap

An unctuous variety of halloysite containing some iron oxide and about 24% water. See also: saponite. Syn: rock soap.

mountain system

A group of mountain ranges exhibiting certain unifying features, such as similarity in form, structure, and alignment, and presumably originating from the same general causes; esp. a series of ranges belonging to an orogenic belt. CF: mountain chain. See also: landform system.

mountain tar

See: mineral tar.

mountain wood

A variety of asbestos that is compact, fibrous, and gray to brown in color, resembling wood. Syn: rockwood.


In power shovel nomenclature, the mounting consists of a frame on which the entire shovel is supported and on which it moves.

mounting pipe

See: column pipe.


A monoclinic mineral, UMo (sub 5) O (sub 12) (OH) (sub 10) ; forms spherulitic masses of radiating purple fibers in incompletely oxidized uranium ores.


A cylindrical fishing tool, fitted with an inward-opening flap valve at the bottom end, used to recover small metal fragments from the bottom of a borehole.


a. The surface outlet of an underground conduit, as of a volcano.

b. The collar of a borehole. c. An opening resembling or likened to a mouth, such as one affording entrance or exit. d. The entrance to a mine. e. The top of a mine shaft or the point of entrance to a slant, drift, or adit. f. The end of a shaft, adit, drift, entry, tunnel, etc., emerging at the surface. g. The opening in a metallurgical furnace through which it is charged; also, the taphole. h. The place of discharge of a stream, as where it enters a larger stream, a lake, or the sea. i. The entrance or opening of a geomorphic feature, such as a cave, valley, or canyon. Z? BOS KSS ��<�� � ' DICTIONARY TERMS:mouthing See: shaft inset. See: shaft inset.

mouth of pit

Aust. The top of a shaft.

movable conveyor

Any of several types of conveyors designed to be moved in a defined path. See also: portable conveyor; shuttle conveyor.

movable jaw

The jaw or slip of a safety or foot clamp; it can be raised or lowered into or out of the body or frame of the clamp either to engage or to disengage the drill rods being run into or pulled out of a borehole. Syn: movable slip.

movable ladder

See: man machine.

movable sieve-type washbox

A washbox in which the screen plate supporting the bed of material under treatment is moved up and down in water.

movable slip

See: movable jaw.


Extension; move to a forward position. Syn: turnover.

moving annual total

In a study of process costs (in large or in detail) a series of costs-per-unit observed and recorded at regular intervals (usually in monthly financial summaries cross referenced to analyzed detail cost). Twelve months are covered and each month the new month's figures are added and those for the corresponding month of the previous year are removed. Therefore, like periods are always compared and seasonal fluctuations are smoothed out. Abbrev., MAT.

moving grizzly

Grizzly in which alternate bars rise and then fall gently, any required lateral (conveying) movement being built into the mechanism, therefore reducing loss of headroom in conveying and screening. Other types are traveling bar, ring-roll, and chain grizzlies.


S. Am. Volcanic mud, sometimes carbonaceous.


An iron with a sharp steel point, for driving into clefts when levering off rock.

M.P.F.M. jet auger

An auger equipped with cutting blades; designed so that fluid, under pressure, passing through inclined holes just above the blades, washes away the material loosened by the blades, thereby cleaning the inside of the casing without disturbing the material below the bottom of the casing that is to be sampled.


The Mining Research Establishment of the National Coal Board, Great Britain. Its prime purpose is to carry out tests and investigations aimed at increasing the efficiency of coal production while maintaining a high level of safety.

MSA distributor

A high-air-pressure directional machine which operates in the manner of a whitewashing machine and displaces coal dust from the roof and sides. This machine carries 2 st (1.8 t) of stone dust, and traveling at 11 ft/min (3.4 m/min) distributes over 26 lb/min (11.8 kg/min) of dust.

MSA methanometer

This methane indicator is one in which the sample is made to flow continuously over the filaments while the determination is being made. In this case, two matched filaments form the adjacent arms of the bridge. One of these is specially activated in order to burn the methane while the other filament is inactive and operates at a somewhat lower temperature. This arrangement is designed to compensate for changes in barometric pressure, temperature, humidity, and the presence of carbon dioxide. Facilities for adjustment are provided to compensate for zero drift and change in battery voltage. The meter is provided with two shunts so that two ranges are provided on the scale: 0% to 5% by 0.1% divisions and 0% to 2% by 0.02% divisions.

MS connector

Nonelectric, short-interval (millisecond, ms) delay device for use in delaying a blast; initiated by detonating cord.


Apprev. for mean spherical candlepower.

M-series core barrel

See: M-design core barrel.