Appendix:Dictionary of Mining, Mineral, and Related Terms/V/2

vibracone
 * A vibrating ore screen in which the feed is from a saucer-shaped distributer onto a conical surface kept in vibration by a ratchet motion.

vibrate
 * To have a swinging or oscillating motion; to move or swing back and forth, such as a pendulum does; to have a period of vibration; to fluctuate; to vacillate; to sound, such as a voice vibrates in an ear; to throb.

vibrating conveyor
 * a. A trough or tube flexibly supported and vibrated at relatively high frequency and small amplitude to convey bulk material or objects. See also: oscillating conveyor.

b. A metal trough mounted on flexible supports and free to move in a vertical plane. It is vibrated at an angle of about 30 degrees to the horizontal. The material being conveyed moves in a series of gentle pitches and catches that blend to produce continuous, uniform flow. There is no tumbling or sliding of the material to cause wear of the trough. There are two basic types of vibrating conveyors: (1) the natural frequency types (those supported by heavy-duty stiff coil or leaf springs), and (2) forced vibration types (those supported by rocker arms or rods pivoted at the trough and at the base connections). Materials can be moved downward, horizontally, or up to 10 degrees slopes. It can convey coal, limestone, sand, coke, granite, gravel, etc. See also: shaker conveyor.

vibrating coring tube
 * A sediment coring tube designed to vibrate in such a way as to overcome the resistance of compacted ocean floor sediments, sands, and gravel.

vibrating grate
 * A stoker developed in Germany and used increasingly in that country and in the United States. The hearth consists of a rigid water-cooled matrix. Coal is fed on to this at one end and is moved across it by the vibrating motion to discharge as ash at the other end. The vibrations, with an amplitude of about 1/8 in (3 mm) and in progress for about 5 s every 2 min give a satisfactory feed rate. The rate of feed is controlled by altering the duration of the vibrations. See also: stoker; underfeed stoker.

vibrating grease table
 * This type table is used at the Kimberly Mines in South Africa for concentrating the -3.33- to +0.59-mm fraction of pan concentrate and other material of +0.59-mm size. Efficiency is 99%, and the ratio of concentration 50,000:1.

vibrating grizzlies
 * Bar grizzlies mounted on eccentrics so that the entire assembly is given a forward and backward movement at a speed of some 100 strokes a minute. This is the type of grizzly now generally used ahead of a primary crusher.

vibrating platform
 * A loading stage or structure with a double vibrating action that causes the coal or minerals to settle down in a mine car while being loaded. This settlement increases the car-carrying capacity and reduces spillage during transit. Syn: tram vibrator.

vibrating screen
 * a. A commercial screen in which the cloth, wire, or bar deck is vibrated by solenoid or by magnetostriction, or mechanically by eccentrics or unbalanced spinning weights.

b. A screen oscillated either by mechanical or electrical means. The amplitude of movement of the vibrating screen is smaller than that of the jigging screen and its speed of oscillation is higher. c. A screen that is vibrated to separate and move pieces resting on it. d. Machines of this type consist of one or more slightly inclined screening surfaces mounted in a robust frame. To increase the capacity and prevent blinding of holes, the screening surfaces are caused to vibrate. This may be done by mounting the screen on powerful springs and causing it to bear down on the underside of the frame. An alternative method used in the Hummer screen is to stretch the wire screen to a high tension and mount an electromagnet actuated by an alternating current at some convenient point on the frame. The magnet works against the springs on which the screen is mounted, and in this way very rapid vibration can be secured and blinding greatly reduced.

vibrating screens (heated)
 * Wire-mesh screens that are vibrated and heated electrically to increase efficiency. See also: screens.

vibrating wire strain gage
 * This consists of a thin steel wire stretched between knife edges, one being free to move longitudinally. The wire is maintained vibrating at its natural frequency by an electrical method. The knife edges are held firmly against the girder under test, a change of strain in the girder varying tension in the wire and hence its natural frequency. This gage is used in conjunction with a reference instrument of fixed frequency; electrical impulses from both instruments are superimposed to produce beats having a frequency equal to the difference between the frequencies of the two instruments. Changes in the frequency of the test gage caused by variations in strain result in identical changes in the beat frequency. The joint output from these two instruments is applied to the plates of a cathode-ray tube, leading to an oscillation of the electron beam with a frequency equal to that of the higher of the two applied frequencies, with an amplitude that increases and decreases with the same frequency as that of the beats.

vibration
 * a. The act of vibrating; oscillation. Vibrations may be free or forced; longitudinal, transverse, torsional, or dilatational; also classified according to kind, such as acoustical, electrical, flexural, etc.

b. The undesirable oscillatory movements of a drill string.

vibration drilling
 * Drilling in which a frequency of vibration in the range of 100 to 20,000 Hz is used to fracture rock. Ultrasonic drilling is one of the better known methods of vibration drilling.

vibration gravimeter
 * A device that measures gravity by observation of the period of transverse vibration of a thin wire tensioned by the weight of a known mass; useful for observation at sea.

vibration meter
 * A seismometer that is used for measuring vibrations of structures from other than seismic causes.

vibration method of roof testing
 * A person's fingertips are placed against the roof, and then the roof is struck a sharp heavy blow. Such a blow usually sets up easily felt vibrations in an unsound roof.

vibration of foundations
 * The foundations of machinery installed in a building should be so designed that the frequency of the machine is two times the natural frequency of the combined system of machines and foundations.

vibration test
 * An approximate grading test for coarse-grained soils. A flat paper-covered board is inclined at a slope of 1:24. The dry and powdered sample of soil is spread in a thin layer across the top of the board. The board is tapped sharply and repeatedly. The soil will travel down the board, the largest particles traveling faster and further than the smaller ones. Dependent on the degree in which the soil spreads out, a grading can be allotted to the soil.

vibrator
 * a. A mechanism imparting vibration to screens, concrete consolidators, and shaking tables.

b. A tool that vibrates at 3,000 to 10,000 cycles per minute. It can be inserted into wet concrete or attached to formwork to compact the concrete. c. A device for attachment to bins or chutes to produce vibration and thus assist in gravity flow of contained material.

vibratory screen
 * A sizing screen similar to the shaking screen, but the reciprocating movement imparted to it is of greater frequency and much smaller amplitude--1,000 rpm and 1/4 in (6.4 mm) being typical. High-frequency vibration is more effective than the slow movement of the shaker in preventing blinding of holes, and the screening is more effective. It may contain one, two, or three screen decks with water sprays for washing products when screening. Five products ranging from plus 3/4 in (19.1 mm) to minus 1/8 in (3.2 mm) are possible from a double-deck screen. In general, the screen is inclined at from 12 degrees to 14 degrees for the coarser sizes and 17 degrees to 21 degrees for the finer sizes with counterflow operation. See also: pool washing screen; varislope screen.

Vibrex grease table
 * A device to concentrate and separate diamonds from gangue material. It is based on the principle that short, sharp vibrations in rapid succession transmitted to a greased surface cause diamonds to become imbedded in the grease, while water washes away other materials.

Vibroflotation
 * The trade name for a geotechnical process that uses vibration to compact clean sands and gravels. The vibration is combined with a water jet to give a high degree of compaction.

vibrograph
 * An instrument for recording the ground vibrations caused by heavy quarry blasts. The relationship between the amount of vibration, the distance from the blast, and the weight of explosive fired may be expressed thus: A = (KE)/D, where A = maximum amplitude in thousandths of an inch; K = constant depending on the quarry site; E = weight of explosive in pounds; and D = distance in feet. The constant K can be determined by firing a specimen blast of a given size at a given distance and measuring the amplitude of the record obtained. Amplitudes in excess of 0.04 in (1 mm) may give rise to damage. A movement of 0.008 in (0.2 mm) can be felt, and if used an excessive number of times may give rise to complaints of nuisance and damage. Short-delay blasting methods with small diameter holes reduce vibration hazards. See also: falling-pin seismometer; seismograph.

vicinal face
 * a. One of the facets modifying normal crystal faces; they usually lie nearly in the plane of the face they modify.

b. One of the crystal faces with complex Miller indices in apparent violation of the Bravais law requiring high densities of lattice points parallel to prominent faces. Vicinal faces are small and diverge from major faces by very small angles. Syn: vicinal form.

vicinal form
 * See: vicinal face.

Vickers' diamond hardness tester
 * A small impression machine, capable of testing very hard metals, finished components, and very thin sheets. The diamond is similar to that used in the diamond pyramid hardness test. The duration of application of the load is controlled automatically, being always applied and removed in exactly the same manner. This machine may also be used with a ball indenter for the Brinell hardness test.

Vickers hardness test
 * A test of resistance to deformation of metals or minerals in which a pyramid-shaped diamond is forced into a polished surface of the specimen to be tested under various static loads. The result is a function of the average length of the diagonals of the resulting indentation. CF: Tukon hardness test; Brinell hardness test.

victualic coupling
 * A development in which a groove is cut around each end of a pipe instead of the usual threads. Two ends of pipe are then lined up and a rubber ring is fitted around the joint. A pair of semicircular bands, forming a sleeve, are placed around the ring and are drawn together with two bolts. These have a ridge on both edges that fits into the groove of the pipe. As they are tightened, the rubber ring is compressed, making a watertight joint, while the ridges fitting in the grooves make it strong mechanically. Victualic pipe is faster to lay because in large sizes it does not have to be aligned perfectly and screwed in.

victualic joint
 * A proprietary pipe joint that allows the pipes to move through several degrees after fixing but yet to remain watertight. This joint is designed to allow about 12 degrees of movement without causing leakage. The pipes have specially shouldered ends that are contained by a circumferential rubber washer held by a special circumferential-type flange. The water has access to the inner part of the washer, on which it exerts pressure and thereby seals the joint.

Vielle-Montagne furnace
 * A mechanical roasting furnace similar to the Ross and Welter type.

Vienna turquoise
 * An amorphous turquoise imitation once manufactured in Austria, Czechoslovakia, France, and England. Having approx. the same chemical composition, hardness, density, and fracture, it is more difficult to detect than the various blue-stained minerals since used as turquoise substitutes.

vierendeel girder
 * An open-frame N-truss without diagonal members, with rigid joints between the top and bottom chords and the verticals. Known also as open-frame girder.

viese
 * Scot. The line of fracture of a fault or the soft earth in a fissure or on the sides of a fault. Also spelled vise.

vignite
 * A magnetic iron ore.

vigorite
 * An explosive resembling dynamite No. 2 and consisting of nitroglycerin with a more or less explosive dope.

Vigorite No. 5
 * Permissible explosive; used in mines. Also called L.F. Vigorite No. 5.

villamaninite
 * An isometric mineral, (Cu,Ni,Co,Fe)(S,Se) (sub 2) ; pyrite group; forms small iron-black cubo-octahedra and radiating nodular masses; at Villamin, Spain.

Villela's reagent
 * An etching reagent consisting of 95 ml of ethyl alcohol, 5 ml of hydrochloric acid, and 1 g of picric acid.

villiaumite
 * An isometric mineral, NaF ; soft; deep carmine; forms small crystals and grains in nepheline syenite; in Islands of Los, Guinea.

vinney
 * Copper ore, with a green efflorescence like verdigris.

vinogradovite
 * A monoclinic mineral, (Na,Ca,K) (sub 4) Ti (sub 4) AlSi (sub 6) O (sub 23) (OH).2H (sub 2) O ; white to colorless; forms crystals and spherical aggregates in nepheline syenite in the Kola Peninsula, Russia.

vinyl acetal resins
 * Prepared from polyvinyl acetate. Properties are toughness, adhesiveness, imperviousness to moisture, and stability toward light and heat. Used as an interlayer in safety glass and as a bonding resin.

violaite
 * A highly pleochroic variety of clinopyroxene found in the Caucasus Mountains, Russia.

violan
 * A violet variety of diopside found at St. Marcel, Piemont, Italy.

violite
 * See: copiapite.

virgate
 * To branch in diverging lines.

virgation
 * a. A divergent, branchlike pattern of fault distribution. The term is used in Russian literature.

b. A fold pattern in which the axial surfaces diverge or fan out from a central bundle. c. A sheaflike pattern, as shown on a map, of mountain ranges diverging from a common center. Ant: syntaxis.

virgin
 * a. Unworked or untouched; said of areas where there has been no mining.

b. An unexploited area or rock formation in which boreholes have not been drilled. c. See: primary metal.

virgin clay
 * Fresh clay, as distinguished from that which has been fired.

virgin coal
 * An area of coal that is in place (in situ) and unimpaired by mining activities.

virgin metal
 * Pure metal obtained directly from ore. See also: primary metal.

viridine
 * A green manganese-rich variety of andalusite.

viridite
 * a. A ferruginous chlorite in chloritic iron ore.

b. A general term formerly applied to indeterminable and obscure green alteration products occurring in scales and threads in the groundmass of porphyritic rocks.

virtual value
 * The calibration of alternating current instruments is based upon what is called the virtual value, and this corresponds to the direct-current value, which would produce the same heating effect in a given resistance. The peak value of alternating voltage or current is 1.4 times greater than the virtual value.

viscometer
 * An instrument used to measure the viscosity. Syn: viscosimeter.

viscosimeter
 * See: viscometer.

viscosity
 * The property of a fluid to offer internal resistance to flow; its internal friction. Specif., the ratio of the shear stress to the rate of shear strain.

viscosity coefficient
 * A numerical factor that measures the internal resistance of a fluid to flow; it equals the shearing force in dynes per square centimeter transmitted from one fluid to another that is 1 cm away, and generated by the difference in fluid velocities of 1 cm/s in the two planes. The greater the resistance to flow, the larger the coefficient. Syn: absolute viscosity; dynamic viscosity.

viscountess
 * Building slate 18 in by 10 in (45.7 cm by 25.4 cm).

viscous
 * a. Adhesive or sticky, having a ropy or glutinous consistency.

b. Imperfectly fluid; designating a substance that, like tar or wax, will change its form under the influence of a deforming force, but not instantly, as more perfect fluids do.

viscous damping
 * Viscous damping is the dissipation of energy that occurs when a particle in a vibrating system is resisted by a force the magnitude of which is a constant, independent of displacement and velocity, and the direction of which is opposite to the direction of the velocity of the particle.

viscous flow
 * A type of fluid flow in which there is a continuous steady motion of the particles; the motion at a fixed point always remains constant. Also called streamline flow; laminar flow; steady flow.

viscous resistance
 * The effect of surface friction between a particle and a liquid when the particle moves through the liquid. CF: turbulent resistance.

Visean
 * Upper Lower Carboniferous.

viseite
 * An isometric mineral, Ca (sub 10) Al (sub 24) (SiO (sub 4) ) (sub 6) (PO (sub 4) ) (sub 7) O (sub 22) F (sub 3) .72H (sub 2) O(?) ; white; forms wartlike masses; at Vise, Belgium.

visibility meters
 * The general principle of such meters is to observe a portion of the visual field against its background and then to bring about a condition such that the observed difference in brightness reaches a threshold value so that it is only just discernible. The instruments differ in their means by which this end is achieved. The threshold may be produced quite simply by interposing a light-absorbing medium, such as an optical wedge, in the field of view. Other methods include reducing the contrast between the object and its background by superimposing a veiling brightness over the observed field.

visible light
 * a. The light of the visible spectrum.

b. Electromagnetic radiation, with wavelength range approx. 4,000 to 7,000 Aa, which a normal human eye can detect. CF: invisible light; ultraviolet; infrared.

visible spectrum
 * That portion of the electromagnetic spectrum in which the waves normally produce, upon the human eye, color sensations of red, orange, yellow, green, blue, violet, or their intermediate hues, or of white light if the rays are combined. Distinguished from radio, infrared, ultraviolet, gamma, and X-rays.

Vissac jig
 * An air-operated pulsator jig in which air is alternately compressed and allowed to expand to produce pulsation. This jig has been used principally on sized bituminous coal.

visual indicator
 * A device by which the winding or haulage engineman can see on a dial or panel the position of the cages in a shaft or the journey on the haulage plane. See also: depth indicator.

Vitasul
 * A trade name for a chemical additive that eliminates or reduces considerably the danger of diesel locomotive fumes underground. Tests have established that the chemical, added to diesel fuel, reduces the carbon-monoxide danger from diesel locomotive exhausts to negligible proportions.

vitiated air
 * Air that has been rendered impure by the breath of workers and horses, or by being mixed with the various gases given off in mines. It is frequently called return air.

vitrain
 * a. Designation of macroscopically recognizable, very bright bands of coals. Very bright bands or lenses, usually a few millimeters (3 to 5) in width; thick bands are rare. Clean to the touch. In many coals, the vitrain is permeated with numerous fine cracks at right angles to stratification and consequently breaks cubically, with conchoidal surfaces. In other coals, the vitrain is crossed by only occasional perpendicular cracks. In the macroscopic description of seams, only the bands of vitrain having a thickness of several millimeters are usually noted. Examination with the microscope shows vitrain to consist of microlithotypes very rich in vitrinite. After clarain, vitrain is the most widely distributed and common macroscopic constituent of humic coals. Occurs in lenticular bands, each derived from a single piece of original vegetable growth. When it constitutes 30% to 60% of total seam, it is termed abundant; more than 60%, dominant; between 15% and 30%, moderate; below 15%, sparse.

b. A coal lithotype characterized macroscopically by brilliant, vitreous luster, black color, and cubic cleavage with conchoidal fracture. Vitrain bands or lenticles are amorphous, usually 3 to 5 mm thick, and their characteristic microlithotype is vitrite. CF: clarain; durain; fusain; vitrite. Syn: pure coal.

vitreous
 * a. In minerals, a luster typical of that of quartz or calcite. CF: adamantine; pearly; resinous.

b. That degree of vitrification evidenced by low water absorption. See also: impermeable; nonvitreous; semivitreous. c. Amorphous. d. Noncrystalline, such as volcanic glass. e. Consisting of or resembling glass.

vitreous copper
 * See: chalcocite.

vitreous copper ore
 * See: chalcocite.

vitreous fusion
 * Gradual fusion; having no sharp melting point.

vitreous silica
 * Silica glass.

vitreous silver
 * See: argentite.

vitric
 * Said of pyroclastic material that is characteristically glassy; i.e., contains more than 75% glass.

vitrics
 * a. Fused siliceous compounds, such as glasses and enamels, as distinguished from ceramics, or fused aluminous compounds.

b. The art or history of glass production.

vitric tuff
 * A tuff that consists predominantly of volcanic glass fragments. CF: crystal tuff; crystal-vitric tuff.

vitrifacture
 * The manufacture of vitreous or vitrified wares, as glass.

vitrifiable
 * Of or pertaining to a substance that can be vitrified.

vitrification
 * An act, or instance, or the process of vitrifying or making glassy; the condition of being vitrified; a vitrified body.

vitrification spalling
 * That resulting directly or indirectly from the permanent physical changes caused by vitrification.

vitrified
 * a. That characteristic of a clay product resulting when the temperature in a kiln is sufficient to fuse all the grains and close all the pores of the clay, making the mass impervious.

b. Converted into glass.

vitrified brick
 * A very hard paving brick burned to the point of vitrification and toughened by annealing.

vitriform
 * Having the form or the appearance of glass; glassy.

vitrify
 * To change into glass or into a glassy substance by heat and fusion. To make vitreous; esp. to produce (as in a ceramic ware) enough glassy phase or close crystallization by high-temperature firing to make nonporous. To undergo vitrification or vitrifaction; to become vitreous.

vitrifying
 * A stage in the heating of a clay when some of the ingredients have melted and have partially or completely closed the pores, as in stoneware and porcelain. The completion of this stage occurs at the point of maximum shrinkage without loss of shape. See also: baking; squotting.

vitrinertite
 * A coal microlithotype that contains a combination of vitrinite and inertinite totalling at least 95%, and containing more of each than of exinite. It generally occurs in high-ranking bituminous coals.

vitrinite
 * A group name comprising collinite and telinite. Differentiation between collinite and telinite depends in part on the method of observation. The distinction is more easily made in thin section or after etching a polished surface. Often there is uncertainty of distinction by reflected light, and in such cases, it is proper to use the general term vitrinite. See also: collinite; telinite.

vitrinization
 * The process in coalification that results in the formation of vitrain. See also: coalification. CF: incorporation; fusinization.

vitrinoid
 * Vitrain and similar material in coal.

vitriol
 * A sulfate of any of various metals (such as copper, iron, or zinc,); esp. a hydrate (as the heptahydrate) of such a sulfate having a glassy appearance or luster.

vitriol ocher
 * See: glockerite.

vitrite
 * A coal microlithotype group that contains vitrinite macerals totalling at least 95%. CF: liptite; vitrain.

vitro-
 * Prefix meaning glassy.

vitroclarain
 * A rock-type coal consisting of vitrinite (collinite or telinite) and other macerals, mainly exinite, and in which the other macerals exceed vitrinite in quantity. CF: clarovitrain.

vitroclastic
 * Pertaining to a pyroclastic rock structure characterized by fragmented bits of glass; also, said of a rock having such a structure.

vitrodurain
 * Durain in which much vitrain is present. Judged obsolete by the Heerlen Congress of 1935. CF: durovitrain.

vitrofusain
 * A coal constituent transitional between vitrain and fusain, and showing plant cell structure. The cell walls are soaked with vitrain, where the cell cavities are empty. It is not a mixture but a transition. Accepted by the Heerlen Congress of 1935 to designate material transitional between vitrain and fusain with fusain being predominant. CF: fusovitrain.

vitrophyre
 * Any porphyritic igneous rock having a glassy groundmass. Adj: vitrophyric. CF: felsophyre; granophyre. Syn: glass porphyry.

vitrophyric
 * Said of a porphyritic igneous rock having large phenocrysts in a glassy groundmass.

vivianite
 * a. A monoclinic mineral, 2[Fe (sub 3) (PO (sub 4) ) (sub 2) .8H (sub 2) O]; colorless where fresh; turning blue on oxidation; soft; a secondary mineral found in ore deposits and pegmatites, in clays associated with bone and other organic remains, and in anaerobic lake sediments. Syn: blue iron earth; blue ocher; Prussian blue.

b. The mineral group annabergite, baricite, hoernesite, koettigite, parasymplesite, and vivianite.

vlasovite
 * A monoclinic and triclinic mineral, Na (sub 2) ZrSi (sub 4) O (sub 11) ; forms colorless crystals in the contact zone of the Lovozero massif, Kola Peninsula, Russia. It is related to narsarsukite.

V-method of roasting
 * The introduction of a supplementary roast heap between each two regular heaps, so that, if left untouched, there would be a continuous and unbroken roast heap the entire length of the roast yard.

vogesite
 * A lamprophyre composed of hornblende phenocrysts in a groundmass of alkali feldspar and hornblende. Clinopyroxene, olivine, and plagioclase feldspar also may be present. Vogesite contains less biotite than minette. The name, given by Rosenbusch in 1887, is for the Vosges Mountains, France.

vogle
 * See: vug.

voglianite
 * a. A soft, green, basic uranium sulfate, found in nodules or as earthy coatings.

b. Validity of species is doubtful. All existing specimens, upon examination, have proved to be cuprosklodowskite. c. A variety of zippeite(?).

voglite
 * A monoclinic mineral, Ca (sub 2) Cu(UO (sub 2) )(CO (sub 3) ) (sub 4) .6H (sub 2) O(?) ; strongly radioactive; emerald to grass green; an alteration product of uraninite associated with liebigite.

void
 * a. A general term for pore space or other openings in rock. In addition to pore space, the term includes vesicles, solution cavities, or any primary or secondary openings. Syn: pore; interstice.

b. That portion of a borehole from which the core could not be recovered.

void ratio
 * The ratio of the volume of void space to the volume of solid substance in any material consisting of voids and solid material, such as a soil sample, sediment, or sedimentary rock. Symbol e. Syn: voids ratio.

voids ratio
 * See: void ratio.

vol
 * See: vole.

volatile
 * Readily vaporizable.

volatile combustibles
 * See: volatile matter.

volatile fluxes
 * The volatile constituents of a magma.

volatile matter
 * In coal, those substances, other than moisture, that are given off as gas and vapor during combustion. Standardized laboratory methods are used in analysis. Syn: volatiles; volatile combustibles.

volatile ratio
 * In coal, the ratio of the volatile matter to the sum of the volatile matter and the fixed carbon.

volatiles
 * The volatile constituents (or rest magma) remaining after the less volatile ores have crystallized as igneous rocks. Syn: volatile matter.

volborthite
 * A monoclinic mineral, Cu (sub 3) V (sub 2) O (sub 7) (OH) (sub 2) .2H (sub 2) O ; radioactive; has one perfect cleavage; dark olive to yellow-green; a secondary mineral with carnotite in sandstone. Syn: uzbekite.

volcanic
 * Characteristic of, pertaining to, situated in or upon, formed in, or derived from volcanoes. See also: extrusive.

volcanic ash
 * See: ash.

volcanic breccia
 * a. A pyroclastic rock that consists of angular volcanic fragments that are larger than 64 mm in diameter and that may or may not have a matrix.

b. A rock that is composed of accidental or nonvolcanic fragments in a volcanic matrix. Syn: alloclastic breccia; lava breccia.

volcanic clay
 * See: bentonite.

volcanic conglomerate
 * A water-deposited conglomerate containing more than 50% volcanic material, esp. coarse pyroclastics.

volcanic dust
 * See: ash.

volcanic earthquake
 * A seismic disturbance that is due to the direct action of volcanic force, or one whose origin lies under or near a volcano, whether active, dormant, or extinct.

volcanic focus
 * The subterranean seat or center of volcanism of a region or of a volcano.

volcanic glass
 * A natural glass produced by the cooling of molten lava, or a liquid fraction of it, too rapidly to permit crystallization. Examples are obsidian, pitchstone, tachylyte, and the glassy mesostasis of many extrusive rocks. CF: glass.

volcanicity
 * See: volcanism.

volcanic ore deposits
 * The major group of ore deposits of magmatic origin, designated as young by European mineralogists, which have been formed under near-surface conditions and very often in Tertiary or younger volcanic rocks. In a strict sense, deposits formed in relation to surface eruptions.

volcanic plain
 * Surface formed by extensive lava or ash flows that cover topographic irregularities.

volcanic rift zone
 * See: rift zone.

volcanic rock
 * a. A generally finely crystalline or glassy igneous rock resulting from volcanic action at or near the Earth's surface, either ejected explosively or extruded as lava; e.g., basalt. The term includes near-surface intrusions that form a part of the volcanic structure. Syn: volcanite.

b. A general term to include the effusive rocks and associated high-level intrusive rocks; they are dominantly basic.

volcanics
 * A general collective term for extrusive igneous and pyroclastic material and rocks.

volcanic water
 * Water in, or derived from, magma at the Earth's surface or at a relatively shallow level; juvenile water of volcanic origin.

volcanism
 * The processes by which magma and its associated gases rise in the crust and are extruded onto the Earth's surface and into the atmosphere. Also spelled vulcanism. Syn: volcanicity.

volcanite
 * An obsolete term variously used to denote a volcanic rock and selenian sulfur.

volcano
 * a. A vent in the surface of the Earth through which magma and associated gases and ash erupt; also, the form or structure, usually conical, that is produced by the ejected material.

b. Any eruption of material; e.g., mud, that resembles a magmatic volcano. Obsolete var; vulcano. Pl: volcanoes. Etymol: the Roman deity of fire, Vulcan.

volchonskoite
 * See: volkonskoite.

vole
 * The place where tin ore is stored to be dried before being put into a smelting furnace. Syn: vol.

voler reductol
 * A lubricant for enclosed gear units; composed of high-quality mineral oil with a suspension of superfine colloidal graphite and silicone foam inhibitor.

volgerite
 * A discredited term equal to stibiconite.

volkonskoite
 * A monoclinic mineral, Ca (sub 0.3) (Cr,Mg,Fe) (sub 2) (Si,Al) (sub 4) O (sub 10) (OH) (sub 2) .4H (sub 2) O ; smectite group. Also spelled volchonskoite.

volley
 * The act of exploding blasts in sections. A round of holes fired at any one time.

volt
 * The practical meter-kilogram-second (mks) unit of electrical potential difference and electromotive force (emf) that equals the difference of potential between two points in a conducting wire carrying a constant current of 1 A when the power dissipated between these two points equals 1 W. It equals the potential difference across a resistance of 1 Omega when 1 A of current is flowing through it; the standard in the United States.

voltage
 * Electromotive force.

voltaite
 * An isometric mineral, K (sub 2) Fe (sub 9) (SO (sub 4) ) (sub 12) .18H (sub 2) O ; has both ferric and ferrous iron.

Volta's list
 * A list or series of metals, such that any one will be at a higher electrical potential when put in contact with any of those that follow, and at a lower potential if in contact with any metal before it in the series.

voltmeter
 * An instrument for determining voltage.

voltzite
 * Wurtzite mixed with an organometallic zinc compound.

volume defect
 * A crystal structure deviating from ideality by having two or more chemical species in one or more crystal sites. CF: crystal defect; disorder.

volume susceptibility
 * See: susceptibility.

volumetric
 * Chemical analysis based upon the reaction of a volume of standard solution with the material being analyzed.

volumetric analysis
 * Quantitative chemical analysis in which known weight of sample is dissolved and reacted with a standard chemical solution of strength proportional to its normality or hydrogen equivalent. Completion of reaction (end point) is judged by change of color, incipient precipitation, or effect on an indicator. See also: dry assay; wet assay.

volumetric efficiency
 * a. The ratio of the total quantity of air passing along the faces to the quantity flowing in the fan drift. See also: overall ventilation efficiency; surface air leakage.

b. The ratio of the volume of air discharged to the displacement for a fan or compressor. c. The volume of water that enters a pump cylinder for each piston stroke divided by the volume swept by the piston (piston area times stroke).

volumetric shrinkage
 * The decrease in volume, expressed as a percentage of the soil mass when dried, of a soil mass when the water content is reduced from a given percentage to the shrinkage limit. Also called volumetric change.

volute
 * a. A spiral casing to a mine fan to provide an area of passage, which gradually increases in proportion to the increasing area of discharge from the fan. See also: evase.

b. A spiral casing for a centrifugal pump or a fan designed so that speed will be converted to pressure without shock.

volute pumps
 * This type of centrifugal pump is the most commonly used. The impellers may be open, closed or semienclosed, single suction, double suction, or nonclogging. They discharge into casings that are progressively expanding spiral designs of one or more stages (multistage). The casings housing the rotating elements may be vertically or horizontally split, and a few designs have casings divided on an angle from the horizontal. Pumps in this class usually have a specific speed below 4,000 rpm with single-suction impellers and a specific speed of 5,000 rpm with double-suction impellers.

von Neumann spike
 * The pressure peak leading the detonation wave prior to the establishment of the C-J state.

vonsenite
 * An orthorhombic mineral, Fe (sub 3) BO (sub 5) ; ludwigite group; contains both ferrous and ferric iron with ferrous iron replaced by magnesium toward ludwigite; black; forms coarse granular masses; at Riverside, CA.

von Sterneck-Askania pendulum
 * A device for measuring the vertical component of gravity, characterized by the use of four pendulums in a single case.

von Wolff's classification
 * A quantitative chemical-mineralogic classification of igneous rocks proposed in 1922 by F. von Wolff.

vooga hole
 * See: vug.

Vooys process
 * A coal-cleaning process using a heavy suspension, consisting of clay and finely ground barite (-150 or #MG200 mesh) in water. A coal containing as little as 3.3% to 3.4% ash is steadily produced, with a yield practically equal to the theoretical float-and-sink yield.

vorobievite
 * A white or rose-colored variety of beryl from the Ural Mountains, Russia, and Madagascar. Syn: morganite. Also spelled vorobyevite.

vortex finder
 * Tube projecting into central vortex of hydrocyclone or dense medium cyclone through which the classified fines or lighter specific gravity fraction of pulp leaves the system.

vraibite
 * An orthorhombic mineral, Tl (sub 4) Hg (sub 3) Sb (sub 2) As (sub 8) S (sub 20) ; forms gray-black crystals or thin red splinters; commonly intergrown with realgar and orpiment; occurs at Salonika, Macedonia, Greece.

vug
 * A small cavity in a rock, usually lined with crystals of a different mineral composition than the enclosing rock. Adj: vuggy. CF: druse; miarolitic cavity; geode. Syn: bug hole; vogle; vooga hole. See also: cavity; vuggy porosity; loch. Etymol: Cornish vooga, cavern or cavity.

vugg
 * A misspelling of vug.

vuggy
 * Pertaining to a vug or having numerous vugs. Syn: vugular.

vuggy lode
 * A lode or vein in which vugs or drusy cavities are of frequent occurrence.

vuggy porosity
 * Porosity due to vugs in calcareous rock. The term vugular is used by some writers but condemned by others. See also: vug.

vugh-arching
 * When a pocket of rock in the periphery of an excavation is weaker than the remainder, it may fail under the ring stress. Fragments split away or fall out until all the weak rock is removed, forming an artificial vugh. This is called vugh-arching.

vug hole
 * See: vug.

vugular
 * See: vuggy.

vulcan coal powder
 * Explosive; used in mines.

vulcanism
 * Volcanism.

vulcanite
 * a. An orthorhombic mineral, CuTe ; with rickardite and native tellurium, it forms coatings on rocks; occurs at the Good Hope Mine, Vulcan, CO.

b. A dark-colored, hard variety of vulcanized India rubber that differs from the softer rubber in having been vulcanized at a high temperature; ebonite. It takes a high polish, and is used for making combs, ornaments, etc., and in electrical work because of its fine insulating properties.

vulcanites
 * A general name for igneous rocks of fine grain size, normally occurring as lava flows, and thus in direct contrast with plutonites.

vulcanized rubber
 * A rubber that has been heated with sulfur to change its properties.

vulcanizing machine
 * Consists essentially of two heavy metal plattens that are placed one on each side of the previously prepared joint and clamped firmly together. Each platten is heated, and this combined application of heat and pressure over a period completes the joint. These machines are used to vulcanize the belt joints of conveyors.

vulcan powder
 * High explosive composed of 30% nitroglycerin, 52.5% sodium nitrate, 10.5% charcoal, and 7% sulfur.

vulpinite
 * A scaly, granular variety of anhydrite; may be admixed with silica; cut and polished for ornamental purposes.

V-vat
 * a. A funnel box; also, having a groove or grooves of a triangular section.

b. See: spitzkasten.

vysotskite
 * A tetragonal mineral, (Pd,Ni)S ; isomorphous with braggite; in minute grains or prisms; at Norilsk, Russia.