Appendix:Dictionary of Mining, Mineral, and Related Terms/X-Y

xalostocite
 * A rose-pink variety of grossularite garnet. Also called rosolite; landerite. From Xalostoc, Morelos, Mex.

xanthate
 * Common specific promoter used in flotation of sulfide ores. A salt or ester of xanthic acid made of an alcohol, carbon disulfide, and an alkali.

xanthiosite
 * A monoclinic mineral, Ni (sub 3) (AsO (sub 4) ) (sub 2) ; sulfur-yellow.

xanthitane
 * a. An alteration product of titanite (sphene).

b. See: anatase.

xanthochroite
 * Amorphous cadmium sulfide. See also: greenockite.

xanthoconite
 * A monoclinic mineral, Ag (sub 3) AsS (sub 3) ; dimorphous with proustite; brilliant red, orange-yellow to brown. Syn: rittingerite.

xanthophyllite
 * See: clintonite.

xanthorthite
 * A yellow altered variety of allanite that contains considerable water.

xanthoxenite
 * A triclinic mineral, Ca (sub 4) Fe (sub 2) (PO (sub 4) ) (sub 4) (OH) (sub 2) .3H (sub 2) O ; wax-yellow; forms thin plates; at Rabenstein, Bavaria, Germany.

xanthus
 * An early name for heliotrope.

x-axis
 * a. The axis of abscissas in a plane Cartesian coordinate system. Commonly written x-axis.

b. One of the three optic axes (x, y, and z) in a biaxial crystal. The x-axis is the axis of a greatest ease of vibration. Light vibrating parallel to the x-axis travels with maximum velocity and is called the fast ray, the x-ray (not to be confused with the penetrating X-rays of extremely short wavelength), and the alpha -ray. The lowest index of refraction n (sub alpha ). in biaxial minerals is the index of the fast ray vibrating parallel to the x-axis. c. One of three axes in a three-dimensional coordinate system. Crystallographers customarily use a right-handed system with the z-axis oriented positive upward, the y-axis positive to the right, and the x-axis positive toward the viewer. For mineral parameters the x-axis is labeled a with periodic translations t (sub 1.

x-coordinate
 * a. An abscissa in a plane Cartesian coordinate system.

b. One of the three coordinates in a three-dimensional rectangular coordinate system.

x-direction
 * One of three orthogonal optic directions in biaxial crystals. Light with its electric vector (vibration direction in early terminology) parallel to the x-direction has the lowest refractive index (n (sub alpha ) ) for a given crystal and is called the fast ray. In orthorhombic crystals, the x-axis is constrained by symmetry to correspond to one of the crystallographic directions, the correspondence determined empirically. In monoclinic crystals, one optic direction, commonly the y-direction, is constrained by symmetry to correspond to the unique diad. In triclinic crystals, there is no symmetrical constraint relating optic directions to crystallographic axes.

xeno-
 * A prefix meaning strange or foreign.

xenoblast
 * A crystal that has grown during metamorphism without the development of its characteristic faces. CF: idioblast. See also: crystalloblast.

xenoblastic
 * Applied to a texture of metamorphic rocks in which the constituent mineral grains lack proper crystal faces.

xenocryst
 * A crystal in an igneous rock that is foreign to the body of rock in which it occurs. CF: xenolith. Syn: accidental inclusion; chadacryst.

xenogenous
 * A little-used syn. of epigenetic.

xenolite
 * A silicate of aluminum, related to fibrolite.

xenolith
 * A foreign inclusion in an igneous rock. CF: autolith; xenocryst. Syn: inclusion; exogenous inclusion; accidental inclusion.

xenomorphic
 * a. Said of the holocrystalline texture of an igneous or metamorphic rock, characterized by crystals not bounded by their own faces but with their forms impressed upon them by adjacent mineral grains. Also said of a rock with such a texture.

b. (Syn: anhedral. in European usage.) Syn: allotriomorphic; anidiomorphic; xenomorphic-granular. CF: automorphic.

xenomorphic-granular
 * See: xenomorphic.

xenon
 * A zero-valent, very heavy, inert gaseous element; one of the so-called noble gases. Symbol, Xe. Obtained by the fractional distillation of liquid air. The gas is used in making electron tubes, stroboscopic lamps, and bactericidal lamps; also used in the atomic energy field in bubble chambers, probes, and other applications where its high molecular weight is of value.

xenothermal
 * Said of a hydrothermal mineral deposit formed at high temperature but shallow depth; also, said of that environment. CF: telethermal; epithermal; mesothermal; hypothermal deposit; leptothermal.

xenotime
 * A tetragonal mineral, YPO (sub 4) ; commonly includes small quantities of thorium, uranium, and rare-earth elements; resembles zircon in form, structure, and occurrence; shows pale tints; an accessory in granites and pegmatites; also occurs in placers.

X-frame brace
 * A brace of a square set in which two diagonal pieces of timber cross to form an X.

xonotlite
 * A monoclinic and triclinic mineral, Ca (sub 6) Si (sub 6) O (sub 17) (OH) (sub 2) ; light-gray to pink; fibrous; in serpentinites in Santa Barbara, CA, and on Isle Royale, MI.

X-ray diffraction
 * Reflection at definite and characteristic angles from space lattices of crystals of X-rays that have been caused to bombard them, thus giving data for identification of characteristic lattice structure of a given species of mineral. See also: reciprocal lattice; diffraction.

xylain
 * a. A subvariety of provitrain in which the woody origin of the cellular structure is microscopically visible. CF: periblain; suberain.

b. Those constituents of coal derived from lignified tissues in which structures were retained.

xylanthite
 * A variety of fossil resin.

xylenite
 * A maceral composed of xylain.

xylinite
 * a. A variety of provitrinite. The micropetrological constituent, or maceral, of xylain. It consists of wood (xylem or lignified tissues) almost jellified in bulk but still showing faint traces of cell walls and resin contents under the microcope.

b. A distinction of telinite, based on botanical origin (xylem or lignified tissues). To be used if desired but considered unnecessary by the Heerlen Congress of 1935. CF: suberinite; telinite.

xylocryptite
 * See: scheererite.

xyloidin
 * An explosive compound produced by the action of nitric acid on starch or woody fiber. Resembles guncotton.

xylopal
 * See: wood opal.

xyloretinite
 * A white hydrocarbon similar to hartite found in fossil wood.

YAG
 * Acronym and abbrev. for yttrium-aluminum garnet.

yard
 * The British standard of length, equal to 36 in, 3 ft, or 0.9144 m.

yardage
 * a. The extra compensation a miner receives in addition to the mining price for working in a narrow place or in deficient coal. Usually at a certain price per yard (or meter) advanced.

b. A system of payment to workers in accordance with the number of yards (or meters) driven, repaired, or packed; the length in yards (or meters) of a drivage or face which a miner or contractor has excavated in a week or from one measuring day to the next. Also called yard work. See also: piecework. c. Relates to cubic yards (or meters) of earth excavated. d. Price paid per yard (or meter) for mining or cutting coal, usually by contract agreement, not on a tonnage basis.

yardage man
 * In bituminous coal mining, a laborer who pries down loose roof rock with a bar after coal has been blasted from the working face; the worker picks out seam partings (layers of rock) in the coal working face prior to blasting, using a long handled pick.

yard price
 * The price paid per yard driven (in addition to tonnage prices) for roads of certain widths and driven in certain directions. See also: yardage.

yard work
 * See: yardage.

yavapaiite
 * A monoclinic mineral, KFe(SO (sub 4) ) (sub 2) ; at the United Verde copper mine, Jerome, AZ. Named for the local Yavapai Native Americans.

y-axis
 * a. One of the three optic axes (x,y, and z) in a biaxial crystal. The y-axis is the intermediate optic axis, at right angles to the plane containing optic axes x and z. Light vibrating parallel to the y-axis is called the intermediate ray, the y-ray, and the beta -ray. The middle-value index of refraction n (sub beta ) in biaxial minerals is the index of the intermediate ray vibrating parallel to the y-axis.

b. One of three axes in a three-dimensional coordinate system. Crystallographers customarily use a right-handed system with the z-axis oriented positive upward, the y-axis positive to the right, and the x-axis positive toward the viewer. For mineral parameters, the y-axis is labelled b with periodic translations t (sub 2). In monoclinic crystal systems, mineralogists conventionally adopt the second setting and designate the unique diad y.

y-coordinate
 * a. An ordinate in a plane Cartesian coordinate system.

b. One of the three coordinates in a three-dimensional rectangular coordinate system.

y-direction
 * a. One of three orthogonal optic directions in biaxial crystals. Light with its electric vector (vibration direction in early terminology) parallel to the y-direction has a unique intermediate refractive index (n (sub beta ) ) for a given crystal and is called the fast ray, relative to light with its electric vector parallel to the z-direction, and the slow ray, relative to light with its electric vector parallel to the x-direction. In orthorhombic crystals, the y-direction is constrained by symmetry to correspond to one of the crystallographic directions, the correspondence determined being empirically. In monoclinic crystals, one optic direction, commonly the y-direction, is constrained by symmetry to correspond to the unique diad. In triclinic crystals, there is no symmetrical constraint relating optic directions to crystallographic axes.

b. One of three orthogonal optic directions in biaxial crystals. Light with its electric vector (vibration direction) parallel to the y-direction has a unique intermediate index of refraction (n (sub beta) ) for a given crystal and is fast or slow depending on crystal orientation.

yeast
 * Fungi belonging to the ascomycetes, in which the usual and dominant growth form is unicellular.

yeatmanite
 * A triclinic mineral, Mn (sub 9) Zn (sub 6) Sb (sub 2) Si (sub 4) O (sub 28) ; forms brown crystals; at Franklin Furnace, NJ.

yellow antimony
 * a. Yellow allotropic form of antimony. Obtained by oxidizing antimony hydride at a low temperature.

b. An unstable form of antimony. It can be obtained during the electrolysis of antimony trichloride, SbCl. As yellow antimony (alpha antimony) is deposited on an electrode, it forms a solid solution in the antimony chloride. When this solution is scratched or heated, metallic antimony (beta antimony) and clouds of antimony chloride form instantaneously, giving rise to the term explosive antimony. There are four allotropic forms of antimony: yellow antimony; black antimony; explosive antimony; and metallic antimony or ordinary antimony. These allotropic forms are also designated alpha antimony (yellow antimony); beta antimony (metallic antimony); and gamma antimony.

yellow arsenic
 * See: orpiment.

yellow boy
 * Deposit from the acid waters of a mine or partial neutralization. Ferrous anhydride and other impurities including fine clay carried down with it.

yellow cake
 * a. Applied to certain uranium concentrates produced by mills. It is the final precipitate formed in the milling process. Usually considered to be ammonium diuranate or sodium diuranate, but the composition is variable and depends on the precipitating conditions.

b. A common form of triuranium octoxide, the powder obtained by evaporating an amnonia solution of the oxide.

yellow coal
 * See: tasmanite.

yellow copper
 * See: chalcopyrite.

yellow copperas
 * See: copiapite.

yellow copper ore
 * See: chalcopyrite.

yellow dog
 * Field name for a drill tripod or derrick lamp, consisting of a metal container with two spouts holding cotton wicks, on which burning oil gives a very yellow light.

yellow earth
 * a. Impure yellow ocher.

b. Loess of northern China.

yellow gravel
 * Eng. The lower subdivision of the Aptian sponge gravel; Faringdon, Berkshire.

yellow ground
 * Oxidized kimberlite of yellowish color found at the surface of diamond pipes (e.g., South Africa), above the zone of blue ground.

yellow heat
 * A division of the color scale. generally given as about 2,000 degrees F (1,090 degrees C).

yellow lead ore
 * See: wulfenite.

yellow ocher
 * a. A mixture of limonite usually with clay and silica. Used as a pigment.

b. A moderate orange yellow that is yellower and darker than deep chrome yellow. c. See: goethite; limonite.

yellow ore
 * See: carnotite; chalcopyrite.

yellow ozokerine
 * A product resembling vaseline, but less homogeneous; produced from crude ozokerite.

yellow pyrite
 * See: chalcopyrite.

yellow ratsbane
 * See: orpiment.

yellow sands
 * Eng. The basal part of the Permian, Durham.

yellow tellurium
 * See: sylvanite. Also spelled yellow tellurim.

yenite
 * A rejected syn. for ilvaite.

yield
 * a. The proportion of coal or ore obtained in mining; the product of a metallurgical process; extraction; recovery.

b. The percentage of "run-of-mine" material that is marketable. c. The amount of a product obtained from any operation expressed as a percentage of the feed material.

yielding arch
 * Steel arch installed in an underground mine. Arches are employed to support loads caused by changing ground movement or faulted and fractured rock. They are designed so that when the ground load exceeds the design load of the arch as installed, yielding takes place in the joint of the arch, permitting the overburden to settle into a natural arch of its own, thus tending to bring all forces into equilibrium.

yielding floor
 * A soft floor that heaves and flows into open spaces when subjected to heavy pressure from packs or pillars. See also: creep.

yielding prop
 * An adjustable steel prop that incorporates a sliding or flexible joint that comes into operation when roof pressure exceeds a set load or value. See also: hydraulic chock; hydraulic prop.

yielding support
 * A support that incorporates a sliding or flexible joint or stilt to accommodate early pressure and thus delays damage and distortion of the support. Friction or hydraulic devices may be used so that a support, when subjected to a load above its set load, yields mechanically rather than by distorting. See also: stilt.

yield loss
 * The difference between the actual yield of a product and the yield theoretically possible (based on the reconstituted feed) of a product with the same properties (usually percentage of ash). Also called washing error.

yield-pillar system
 * A method of roof control whereby the natural strength of the roof strata is maintained by relieving pressure in working areas and controlling transference of load to abutments that are clear of workings and roadways. The method consists of causing certain coal pillars to yield in small amounts. See also: double packing.

yield point
 * The differential stress at which permanent deformation first occurs in a material. Syn: yield stress; yield strength.

yield strength
 * The stress at which a material exhibits a specified deviation from proportionality of stress and strain. An offset of 0.2% is used for many metals. See also: yield point.

yield stress
 * a. The lowest stress at which extension of a tensile test piece increases without increase in load. It is determined by observing the fall of the testing lever and checked by a pair of dividers on the original gage length. Many materials do not indicate a defined yield stress and in such cases the proof stress is used. See also: working stress; high-tensile steel; mild steel; yield point.

b. Minimum stress required to shear (that is, exceed elastic recovery) a suspension, such as the dense media used in mineral concentration.

YIG
 * Acronym and abbrev. for yttrium-iron garnet.

yoderite
 * A monoclinic mineral, (Mg,Al) (sub 8) Si (sub 4) (O,OH) (sub 20) ; purple; highly pleochroic; in a quartz-yoderite-kyanite-talc schist at Mautia Hill, Kongwa, Tanzania.

Yogo sapphire
 * Dark-blue corundum from Yogo Gulch, MT.

yoke
 * a. An interconnecting link between the twin cylinders of a hydraulic-feed diamond drill through which the action of the hydraulic-feed cylinders is transmitted to the drill rods and bit.

b. A clamp fitted to the casing at the collar of a drill hole, which when anchored by means of wedge bolts prevents grout pressure from forcing the casing out of the hole.

yolk
 * Nodule; occurs at Forest of Dean, U.K.

Yorkian
 * A term which has been proposed (instead of Westphalian) for the Coal Measures strata between the Lanarkian and the Staffordian.

yoshimuraite
 * A triclinic mineral, (Ba,Sr) (sub 2) TiMn (sub 2) (SiO (sub 4) ) (sub 2) (PO (sub 4) ,SO (sub 4) )(OH,Cl) ; forms orange-brown tabular crystals or stellate groups; occurs in an alkali pegmatite at the Noda-Tamagawa Mine, Iwate prefecture, and the Taguchi Mine, Aichi Prefecture, Japan.

yowah nut
 * Walnut-to almond-size pebble with an opal center; ironstone covered with a thin band of opal, or hollow; near Yowah station, western Queensland, Australia. A subvariety of boulder opal.

ytterbite
 * See: gadolinite.

ytterbium
 * A rare-earth element that has a bright silvery luster, is soft, malleable and quite ductile. Symbol, Yb. Occurs with other rare-earths in a number of rare minerals. Commercially recovered from monazite sand. Has a possible use in improving the mechanical properties of stainless steel; few other uses have been found.

yttergranat
 * A calcium-iron garnet containing a small amount of yttria. A variety of andradite.

yttrialite
 * A possibly hexagonal mineral, (Y,Th) (sub 2) Si (sub 2) O (sub 7) ; olive green tarnishing to orange-yellow; occurs in Texas.

yttrium
 * A rare-earth element that has a silvery-metallic luster. Symbol, Y. Occurs in nearly all of the rare-earth minerals. Recovered commercially from monazite sand and from bastnasite. Widely used: in color television tubes; to reduce the grain size in chromium, molybdenum, zirconium, and titanium; to increase the strength of aluminum and magnesium alloys; as a deoxidizer for vanadium and other nonferrous metals; in nuclear technology for its high neutron transparency.

yttrium-aluminum garnet
 * Synthetic; Y (sub 3) Al (sub 5) O (sub 12) ; has useful magnetic properties. Actually not a true garnet and should not be confused with any of the silicate minerals called garnets in the garnet group of minerals. Manufacture of yttrium-aluminum garnets is a commercial use of yttrium. Used in lasers and in microwaves and other electronic applications. Acronym and abbrev., yag.

yttrium garnet
 * A variety of garnet containing a small amount of yttrium earths. Syn: yttrogarnet. See also: yttergranat.

yttrium-iron garnet
 * Synthetic; Y (sub 3) Fe (sub 5) O (sub 12) ; has useful magnetic properties. Actually not a true garnet and should not be confused with any of the silicate minerals called garnets in the garnet group of minerals. Manufacture of yttrium-iron garnets is a leading commercial use of yttrium. Used as electronic transmitters, as filters for selecting or tuning microwaves, and as transmitters and transducers of acoustic energy. Acronym and abbrev., yig.

yttrocrasite
 * An orthorhombic mineral, (Y,Th,Ca,U)(Ti,Fe) (sub 2) (O,OH) (sub 6) ; also contains Th, U, Fe; radioactive; black altering to a dull brown coating; in granite pegmatites.

yttrogarnet
 * See: yttrium garnet.

yttromicrolite
 * A discredited mineral name for an amorphous mixture of calcium sulfate, tantalite, and heterogeneous microlite.

yttro-orthite
 * See: allanite.

yttrotantalite
 * An orthorhombic mineral, (Y,U,Fe) (Ta,Nb)O (sub 4) ; radioactive; black to brown: in pegmatites.

yttrotungstite
 * A monoclinic mineral, YW (sub 2) O (sub 6) (OH) (sub 3) . Syn: thorotungstite.

yugawaralite
 * A monoclinic mineral, CaAl (sub 2) Si (sub 6) O (sub 16) .4H (sub 2) O ; zeolite group; colorless to white; in low-grade metamorphosed tuffs near the Yugawara hot spring, Kanagawa, Japan.

yukonite
 * a. A noncrystalline mineral: Ca (sub 2) Fe (sub 3) (AsO (sub 4) ) (sub 4) OH.12H (sub 2) O.

b. An obsolete term originally assigned to an igneous rock intermediate in composition between a tonalite and an aplite. It is named after the Yukon River, Alaska.