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

hod
 * a. Forest of Dean. A cart or sled for conveying coal in the stalls of thin seams.

b. A tray or trough with a pole handle that is borne on the shoulder, for carrying mortar, brick, or similar load.

hodge jig
 * Variation on Harz jig in which the plunger (piston) has differential motion. See also: Harz jig.

hoedown
 * See: breakdown.

hoegbomite
 * See: hoegbomite.

hoelite
 * An orthorhombic mineral, C (sub 14) H (sub 8) O (sub 2) ; forms delicate yellow needles associated with chlorides and sulfur deposited by gases at a burning coalbed on Spitzbergen Island (anthraquinone).

hoernesite
 * A monoclinic mineral, (Mg (sub 3) (AsO (sub 4) ) (sub 2) .8H (sub 2) O); vivianite group, with Mg replaced by Co toward erythrite; in white crystals resembling gypsum; also columnar; a secondary mineral formed by alteration of arsenate minerals. Syn: hoernesite.

Hoesch process
 * A method of working the open-hearth furnace in the duplex process so as to reduce as much as possible the amount of manganese lost in the slag in the production of manganese steels.

hoe scraper
 * In mining, scraper-loader used to gather and transport severed rock. Cables pull a box-sided hoe over the loose ore, which is gathered and dragged (slushed) to the delivery point.

Hoganas process
 * A method for the production of sponge iron that consists of charging fireclay pots with flat briquettes of a concentrate of iron ore interspersed with layers of carbon, prepared by mixing coal with coke breeze; the pots are charged in batches in a long pit furnace where they are heated to about 1,200 degrees C.

hogback
 * a. Any ridge with a sharp summit and steep slopes of nearly equal inclination on both flanks, and resembling in outline the back of a hog; specif. a sharp-crested ridge formed by the outcropping edges of steeply inclined resistant rocks, and produced by differential erosion. The term is usually restricted to ridges carved from beds dipping at angles greater than 20 degrees . CF: cuesta.

b. A term applied in New England to a drumlin (western Massachusetts) and to a horseback or esker (Maine). c. The name given by geologists to the ridgy structure of certain districts, which consist of alternate ridges and ravines, occasioned either by the sharp undulations of the subjacent rocks, or more frequently by the erosive action of mountain torrents that cut out the ravines and leave the ridges or "hog's-backs" standing between. This structure occurs most abundantly on the lower slopes and flanks of mountain ranges. d. A sharp anticlinal, decreasing in height at both ends until it runs out. e. A ridge produced by highly tilted strata. f. Local term for drumlins in western Massachusetts. g. A name applied in the Rocky Mountain Region to a sharp-crested ridge formed by a hard bed of rock that digs rather steeply downward. h. A ridge or lines of high hills with sharp summits and steeply sloping sides. i. Eng. A sharp rise in the floor of a coal seam.

hoegbomite
 * A trigonal and hexagonal mineral, (Mg,Fe) (sub 2) (Al,Ti) (sub 5) O (sub 10) ; metallic black with imperfect cleavage and conchoidal fracture; with magnetite, ilmenite, corundum, or ferroan spinel in iron ore at Redstand, Norway, and in emery at Whittles, VA. Also spelled hoegbomite.

hoggan
 * Corn. The food carried by the miner to the mine.

hogger
 * Scot. A leather or canvas delivery pipe at the top of a sinking set of pumps.

hogger pipe
 * N. of Eng. The upper terminal pipe with delivery hose from the mining pump.

hogger pump
 * The topmost pump in a shaft.

hoggin
 * A material composed of screenings or siftings of gravel or a mixture of loam, coarse sand, and fine gravel, used in making filter beds, as a binder, etc.

hogging moment
 * A bending moment that tends to cause hog. See also: sagging moment.

hohmannite
 * Probably amarantite. See also: metahohmannite.

hoist
 * a. The windlass mechanism incorporated as an integral part of a power-driven drilling machine used to handle, hoist, and lower drill-string equipment, casing, pipe, etc., while drilling, or to snake the drill from place to place.

b. The act or process of lifting drill string, casing, or pipe out of a borehole. c. A power-driven windlass for raising ore, rock, or other material from a mine and for lowering or raising people and material. Also called hoister. Syn: mine hoist. d. The mechanism by which a bucket or blade is lifted, or the process of lifting it. e. A drum on which hoisting rope is wound in the engine house, as the cage or skip is raised in the hoisting shaft. f. An engine with a drum, used for winding up a load from a shaft. See also: winding engine. g. The amount of ore, coal, etc., hoisted during a shift. h. See: draw works; elevator.

hoist back-out switch
 * A switch that permits operation of the hoist only in the reverse direction in case of overwind. Syn: back-out switch.

hoist boy
 * In bituminous coal mining for Arkansas and Oklahoma, a general term applied to a hoisting engineer who operates a small hoisting engine, or an oiler who lubricates and cleans the engine.

hoist engineer
 * See: hoistman.

hoist engineman
 * See: hoistman.

hoister
 * A machine used in hoisting the product.

hoisting
 * a. Winding in a mine.

b. In power-shovel nomenclature, hoisting is a term applied to two operations: (1) the raising or lowering of the boom, and (2) the lifting or dropping of the dipper stick in relation to the boom.

hoisting block
 * a. The lower block of a block and fall, bearing the hoisting hook.

b. Used incorrectly as a syn. for sheave wheel. c. A traveling block or sheave.

hoisting compartment
 * The section of a mine shaft used for hoisting the mineral to the surface.

hoisting crab
 * A crab, winch, or windlass for hoisting.

hoisting cycle
 * The periods of acceleration, uniform speed, retardation, and rest. The deeper the shaft, the greater is the ratio of the time of full-speed hoisting to the total hoisting cycle. For shallow shafts there may be very little time at full speed, retardation beginning almost at the end of the accelerating period.

hoisting drum
 * The flanged cylindrical part of a windlass around and on which the hoist rope or cable is wound. Also called spool.

hoisting engineer
 * One who operates a hoisting engine, esp. at a mine or quarry. Also called engineman. See also: hoistman.

hoisting jack
 * A device for applying hand power to lift an object by means of a screw or lever, or by hydraulic power.

hoisting plug
 * A pin-thread heavy-bodied coupling provided with a swivel-mounted eye in the end opposite the pin-thread end. When attached to the hook on the drill-hoist line, the pin-thread end can be screwed into the rods to hoist and otherwise handle drill-string equipment when making borehole round trips. Also called swivel plug. See also: plug. Syn: screwplug.

hoisting power
 * The capacity of the hoisting mechanism on a drill machine. May be expressed in terms of the number of lineal feet of a specific-size drill rod a hoist can lift on a single line or in terms of the total weight it can handle, figured in pounds or tons.

hoisting rope
 * A rope composed of a sufficient number of wires and strands to ensure strength and flexibility. Such ropes are used in shafts, elevators, quarries, etc.

hoisting sheave
 * See: winding sheave.

hoistman
 * In mining, a person who operates steam or electric hoisting machinery used to lower cages (elevators) and skips (large, metal, boxlike containers) into a mine and to raise them to the surface from different levels. May be designated according to type of power used, as electric-hoist person or steamhoist person. Also called cageman; cage runner; hoist engineer; hoist engineman; hoisting engineer; hoisting engineman; hoist operator; operating engineer; shaft driver; shaft engineer; shaft-hoist engineer; shaft hoistman.

hoist operator
 * a. In petroleum production, one who lowers and raises surveying, servicing, or testing instruments in and out of oil or gas wells on electrical conductor cables, using truck-mounted hoisting equipment. Also called winch operator.

b. See: hoistman.

hoist overspeed device
 * A device that can be set to prevent the operation of a mine hoist at speeds greater than predetermined values and usually causes an emergency brake application when the predetermined speed is exceeded.

hoist overwind device
 * A device that can be set to cause an emergency brake application when a cage or skip travels beyond a predetermined point into a danger zone.

hoist signal code
 * Prescribed signals for indicating to the hoist operator the desired direction of travel and whether people or materials are to be hoisted or lowered in mines.

hoist signal system
 * A system whereby signals can be transmitted to the hoist operator (and in some instances by the operator to the cager) for control of mine hoisting operations.

hoist slack brake switch
 * A device for automatically cutting off the power from the hoist motor and causing the brake to be set in case the links in the brake rigging require tightening or the brakes require relining.

hoist trip recorder
 * A device that graphically records information such as the time and number of hoists made as well as the delays of idle periods between hoists. Syn: trip recorder.

holdback
 * On an inclined belt conveyor system, a brake that comes automatically into use in the event of power failure, thus preventing the loaded belt from running downward and piling up rock.

Holdcroft thermoscope bar
 * Temperature indicator that consists of a series of small bars placed horizontally on a refractory stand. On heating, some bars are bent to varying degrees, while others are unaffected. The temperature is indicated by the bar that is just beginning to sag. The bars are numbered 1 to 40, the temperature range being 600 to 1,550 degrees C. See also: thermoscopic bar.

holdenite
 * An orthorhombic mineral, (Mn,Mg) (sub 6) Zn (sub 3) (AsO (sub 4) ) (sub 2) (SiO (sub 4) )(OH) (sub 8) ; in zinc deposits at Franklin, NJ.

holdfast
 * Temporary anchorage for guy ropes.

holding
 * a. See: take.

b. Also Syn: mining claim. under General Mining Law of 1872, (Act. of May 10, 1872; 17 Stat. 91) See also: undercut.

holding-down bolt
 * See: anchor bolt.

holding rope
 * Support rope for suspension of a grab used for excavating or handling bulk material.

hold out!
 * Derb. An exclamation by the banksperson down a shaft to the bottomer, when workers are about to descend the shaft, to let them know that they are not to send up a load of coal, but merely the empty rope or chain.

hole
 * a. In Joplin, Missouri, a local term for a mine shaft.

b. A drill hole, borehole, or well. See also: borehole. c. To undercut a seam of coal by hand or machine. d. To make a communication from one part of a mine to another. e. To pick out the soft clay beneath a lode or seam of coal preparatory to wedging or blasting the mass out. f. A perforation through the laminae.

hole curvature
 * The amount, expressed in degrees, that a borehole has diverged from its intended course in a distance of 100 ft (30 m). Syn: hole deviation.

hole deviation
 * See: hole curvature.

hole-in
 * To start drilling a borehole. Also called collar; spud; spud-in.

hole layout
 * In quarrying, an arrangement consisting of a combination of vertical and horizontal holes.

holeman
 * Pennsylvania. Person who loads holes with explosives; a charger.

holers
 * The workers employed in the operation of holing the coal.

hole system
 * A system of contract work underground by which the pointing of the holes and blasting are done by company personnel and the rest of the work by the miners.

hole through
 * Successful meeting of two approaching tunnel heads, or of winze and raise.

holing
 * a. Cutting.

b. The working of a lower part of a bed of coal for bringing down the upper mass. c. The final act of connecting two workings underground. See also: holing-through. d. The meeting of two roadways driven expressly to intersect each other. Syn: thirling. e. Eng. Shale partings in which the first charges were inserted for blasting, Wenlock limestone, Dudley. f. See: undercutting. g. Eng. See: kirving.

holing about
 * Eng. The operation of establishing an air current between the downcast and upcast shafts.

holing nog
 * A kerf wedge.

holing pick
 * A pick used in holing coal.

holings
 * Eng. Holing dirt or small coal made by kirving with a coal-cutting machine. Also called scuffings. Syn: cuttings.

holing shovel
 * S. Staff. A short-handled, round-bladed shovel.

holing-through
 * Driving a passage through to make connection with another part of the same workings, or with those in an adjacent mine. See also: holing.

Holland-Gaddy formula
 * A coal pillar design formula that predicts the strength of coal pillars based on laboratory tests of coal cube strength combined with pillar height and width specifications. The Holland-Gaddy formula is generally considered to be overly conservative for large pillar width-to-height ratios (over 5).

hollandite
 * A monoclinic mineral, BaMn (sub 8) O (sub 16) ; cryptomelane group; pseudotetragonal; massive, botryoidal, stalactitic, or prismatic with deeply striated faces; commonly associated with pyrolusite. CF: romanechite.

hollow dam
 * A dam built of reinforced concrete, mass concrete, or masonry in which the water pressure is resisted by a sloping slab or vault carried by buttresses.

hollow-plunger pump
 * A pump used for mining and quarrying, as in muddy and gritty water.

hollow quoin
 * Recessed masonry that carries the heel post of a lock gate.

hollow-rod churn drill
 * A churn drill in which hollow rods replace the steel wire rope. The drilling fluid is pumped down the inside of the rods, and the chipping and fluid return to the surface on the outside.

hollows
 * Eng. Old abandoned workings.

Holman Airleg
 * A drill support consisting of a cylinder of about 2-in (5.1-cm) bore in which the piston is actuated by compressed air controlled by a twist-grip control valve. This valve is also used to release the air pressure to allow the piston to be lowered. The control valve also regulates the feeding pressure on the drill. The length of feed of the Holman Airleg is 39 in (99 cm), overall length 57 in (145 cm), and weight 25 lb (11.4 kg). A vent hole near the top of the cylinder allows the air to escape when the piston travels past it, so as to warn the operator that the limit of feed has been reached. The leg is then readjusted for drilling to be resumed. The leg gives good support to the drill at all heights within reasonable limits, and one person can comfortably handle a drill when mounted in this way.

Holman counterbalanced drill rig
 * A drill rig consisting of a rail-track carriage on which is mounted a counterbalanced boom 10 ft (3 m) in length. For two-drill mounting, a crossbar is attached to the boom, and drill cradles can be fixed over or under the bar by swinging it through 180 degrees . For a four-drill mounting, two additional vertical columns are used; these are jacked to the floor and the drill carriage clamped to the track. The crossbars can be clamped to any required position on the vertical columns.

Holman dust extractor
 * A dust trap in which the dust and chippings created during percussive drilling are drawn back through the hollow drill rod and out through the rear of the machine and along a hose to a metal container with filter elements. The appliance requires a special type of drilling machine, rods, and bits. See also: dust trap.

Holmberg system
 * A method of sintering iron ore. Sintering is carried out in a series of pans, 11 ft 6 in (3.5 m) square, with robust chromium vanadium steel grate bars, which have a life of 5 to 6 years. Advantages include low fuel consumption and absence of moving parts in the sintering zones.

Holme mud sampler
 * A device that takes samples with a scoop rotating on an axle mounted on a heavy frame that rests firmly on the bottom. The device is lowered open with the entire weight taken by a shackle on a balanced arm. Closure is not effected on touching bottom. On hoisting, the pressure of water on a vane attached to the balanced arm tips a lever allowing a pin to slip out, releasing the shackle. The weight is then transferred to a rope rotating around a large drum. This in turn rotates a small pulley and drags the sampling hemisphere through the bottom via a second pulley to which it is attached by a light wire. The maximum volume of the sample is 5� L, and in practice, usually about 3 to 4 L are collected.

Holme suction grab
 * A sampling device using force provided by a vacuum chamber (containing air at atmospheric pressure) to suck in a sediment sample. On striking the bottom, the chamber is put into communication with the outside. Water pressure forces the sample into the collecting tube. The pressure chamber itself is a strong brass tube closed at the upper end by a lid and held firmly in position by a clamp. A sampling tube is fixed below the chamber and extends upward into it. Between the upper and lower parts of the central tube is a plug held in position by retaining hooks through slots in the wall of the lower tube. When the device strikes the bottom, a mouth tube rises, disengaging the plug, which flies up the tube. The water then forces material up into the collecting tube.

holmquistite
 * An orthorhombic mineral, Li (sub 2) (Fe,Mg) (sub 3) Al (sub 2) Si (sub 8) O (sub 22) (OH) (sub 2) ; amphibole group, with Mg/(Mg+Fe (super 2+) ) = 0.1 to 0.89 ; in granite pegmatites.

Holocene
 * An epoch of the Quaternary period, from the end of the Pleistocene, approx. 10,000 years ago, to the present time; also, the corresponding series of rocks and deposits. When the Quaternary is designated as an era, the Holocene is considered to be a period. Syn: Recent.

holocrystalline
 * Said of the texture of an igneous rock composed entirely of crystals, i.e., having no glassy part. Also, said of a rock with such a texture.

holohedral
 * The point group with the highest symmetry of its crystal system. CF: hemihedral; merohedral; crystallographic system.

holohyaline
 * Said of an igneous rock that is composed entirely of glass.

hololeims
 * Coalified remains of entire plants.

holystone
 * a. A soft sandstone used to scrub a ship's decks.

b. To scrub with a holystone. c. Eng. Limestone full of holes, white limestones of the Great Oolite near Minchinhampton, Gloucestershire, used for megalithic monuments. d. Pumice or friable sandstone used to scrub a ship's deck.

home
 * N. of Eng. In the direction of, or toward, the shaft, as in an underground mine. Outby.

homeoblastic
 * Pertaining to a type of crystalloblastic texture in a metamorphic rock in which the essential mineral constituents are approx. of equal size. CF: crystalloblastic; heteroblastic.

homeothrausmatic
 * A genetic term applied to igneous rocks with an orbicular texture in which the nuclei of the orbicules are formed of inclusions of the same generation as the groundmass. CF: isothrausmatic; heterothrausmatic; crystallothrausmatic.

homocline
 * A general term for a series of rock strata having the same dip, e.g., one limb of a fold, a tilted fault block, or an isocline. CF: monocline. Adj: homoclinal.

homoeomorphism
 * A near similarity of crystalline forms between unlike chemical compounds.

homogeneity
 * In geochemical prospecting, the homogeneity of a geochemical anomaly is a measure of the smoothness, or absence of strong local variations, in the distribution of the indicator element.

homogeneous
 * Made up of similar parts or elements; of the same composition or structure throughout; uniform. Opposite of heterogeneous.

homogeneous mass
 * A mass that exhibits essentially the same physical properties at every point throughout the mass.

homopolar crystal
 * A crystal characterized by covalent bonding--the type of atomic bonding resulting from the sharing of electrons by neighboring atoms.

homoseismal line
 * Line on the Earth's surface connecting points where the seismic wave arrives, generated by an earthquake, at the same time.

homotropal ventilation
 * Ventilation by a current of air traveling in the same direction as the flow of mineral out of a mine. See also: descensional ventilation; ascensional ventilation; antitropal ventilation.

hondurasite
 * Formerly called selen-tellurium (Se,Te), a variety of the trigonal mineral form of tellurium, Te.

honeycomb
 * Any substance, as cast iron, worm-eaten wood, etc., having cells suggesting a honeycomb; also applied to certain rock structures.

honeycomb structure
 * An arrangement of soil particles having a comparatively loose, stable structure resembling a honeycomb. See also: soil structure; flocculent structure; single-grained structure.

honeycomb weathering
 * A type of chemical weathering in which innumerable pits are produced on a rock exposure. The pitted surface resembles an enlarged honeycomb and is characteristic of finely granular rocks, such as tuffs and sandstones, in an arid region.

honey stone
 * A mellate of aluminum, Al (sub 2) [C (sub 6) (COO) (sub 6) ].16H2) O, of yellowish or reddish color, and a resinous aspect, crystallizing in octahedrons with a square base. See also: mellite.

Honigmann process
 * A continental method of shaft sinking through sand that is water bearing. The shaft is formed by boring in stages, increasing in size from the pilot hole of about 4 ft (1.2 m) in diameter to the final excavation size. Once the shaft is bored, mud flush circulation continues while the lining is lowered. The lining consists of two steel cylinders, one within the other, and the annular space is filled with concrete. The cylinders are lowered into the shaft, and 10-ft (3-m) lengths are added and welded in position at the shaft top.

hoodoo
 * A fantastic column, pinnacle, or pillar of rock produced in a region of sporadic heavy rainfall by differential weathering or erosion of horizontal strata, facilitated by joints and by layers of varying hardness, and occurring in varied and often eccentric or grotesque forms. Syn: rock pillar.

hook block
 * The lower sheave or block, on a crane hoist, to which a swivel hook is attached.

Hooke's law
 * A statement of elastic deformation, that the strain is linearly proportional to the applied stress. See also: elasticity.

hook forward method
 * A method of lashing on to the rope in which the chain, after lapping two to five times around the rope, depending on the load and the inclination, is brought forward across the laps and threaded through the hook at the front. This method keeps the last lap tight and prevents the laps from spreading.

hook-on
 * The worker who adjusts cables or chains about objects to be lifted; places hook of crane block in bucket bails, and hooks winches to objects to be moved, etc.

hook tender
 * In bituminous coal mining, a laborer who attaches the hook at the end of a hoisting cable to the link of the leading or near car of a trip of cars to be hauled up or lowered down an incline in the mine or at the surface. Also called rope cutter.

Hoolamite indicator
 * A carbon monoxide detector consisting essentially of a small glass tube filled with a powdered chemical; when air is drawn through it, if any of the gas is present, the powder will change color, its degree of change depending upon the amount of carbon monoxide present. This device is very sensitive and will detect gas as low as 0.01%.

Hooper jig
 * Pneumatic jig, used in regions where water is scarce, or where the ore must be kept dry, to concentrate values from sands.

Hoope's process
 * An electrolytic process of aluminum refining that utilizes three liquid layers in the reduction cell. An anode of aluminum-copper alloy is used in a fused fluoride bath. The lighter aluminum, about 99.99% purity, collects at the cathode above the fused bath.

Hopcalite
 * Catalytic granules consisting of finely divided manganese dioxide mixed with copper oxide and a small quantity of silver oxide, and used in gas mask cannisters to remove carbon monoxide by oxidizing it to carbon dioxide. With the development of Hopcalite, the problem of providing adequate protection against carbon monoxide poisoning was solved.

hopeite
 * An orthorhombic mineral, Zn (sub 3) (PO (sub 4) ) (sub 2) .4H (sub 2) O ; dimorphous with parahopeite; in minute grayish-white crystals with zinc ores, esp. at Broken Hill, Zimbabwe.

Hopfner process
 * A process for the recovery of copper in which a solution of cuprous chloride in sodium or calcium chloride is used to dissolve copper sulfides. The solution is then electrolyzed in tanks with diaphragms. The anodes are impure copper; the cathodes, pure copper. Copper is deposited from the cuprous chloride solution, and cupric chloride is regenerated.

Hopkinson chain machine
 * An electrically driven chain coal cutter designed and manufactured by Mather and Platt in 1901 with provision for slewing the jib. A large number of these machines were built. For many years the Hopkinson was the only chain coal cutter built in the United Kingdom.

hopper
 * a. A vessel into which materials are fed, usually constructed in the form of an inverted pyramid or cone terminating in an opening through which the materials are discharged (not primarily intended for storage).

b. Surge bin placed at discharge end of intermittent transporting system that handles dry ore or rock; used to smooth out and regulate delivery from that point. A hopper car is one with bottom discharge gear and insloping side walls. c. A storage bin or a funnel that is loaded from the top and discharges through a door or chute in the bottom. d. A container or bin for broken ore. e. A place of deposit for coal or ore.

hopper car
 * A car for coal, gravel, etc., shaped like a hopper, with an opening to discharge the contents.

hopper crystal
 * A crystal with edges grown beyond face centers. CF: skeletal crystal.

hopper dredge
 * A hydraulic dredge that operates in cycles, alternately filling at a dredge site and traveling to and from a disposal or offloading site.

hopperings
 * In gold washing, gravel retained in the hopper of a cradle.

hoppers
 * Pockets at the bottom of a breaker through which the processed coal falls as it is loaded into railroad cars; also the cars.

hopper salt
 * Grainer or solar salt produced in characteristic hollow-faced cubes by surface evaporation.

hopper table
 * Early type of pneumatic table used in ore treatment.

hoppet
 * A vessel for measuring ore.

hoppit
 * A large bucket used in shaft sinking for hoisting men, rock, materials, and tools. Since about 1955, hoppit sizes have increased to about 80 ft (super 3) (2.3 m (super 3) ) and in some cases to 110 ft (super 3) (2.5 m (super 3) ) and surface tipping facilities have been brought to a high degree of efficiency to cope with large-diameter shafts and fast sinking rates. See also: cactus grab.

horadiam
 * a. The drilling of a number of horizontal boreholes radiating outward from a common center; a single drill site or drill setup.

b. See: horizontal-ring drilling.

horizon
 * a. An interface indicative of a particular position in a stratigraphic sequence. In practice it is commonly a distinctive, very thin bed or marker. See also: marker bed.

b. One of several lines or planes used as reference for observation and measurement relative to a given location on the Earth's surface and referred generally to a horizontal direction (Huschke, 1959); esp. apparent horizon. The term is also frequently applied to artificial horizon. c. One of the layers of the soil profile, distinguished principally by its texture, color, structure, and chemical content, designated as A-horizon; B-horizon; C-horizon. d. An identifiable rock stratum regionally known to contain or be associated with rock containing valuable minerals. CF: marker; marker bed. e. See: soil horizon.

horizon mining
 * A system of mine development that is suitable for inclined, and perhaps faulted, coal seams. Main stone headings are driven, at predetermined levels, from the winding shaft to intersect and gain access to the seams to be developed. The stone headings, or horizons, are from 100 to 200 yd (91.44 to 182.88 m) vertically apart, depending on the seams available and their inclination. The life of each horizon ranges from 10 to 30 years. Connections between horizons at inby points are by staple shafts or drivages in the coal. Also called horizontal mining; continental mining. See also: lateral. CF: in-the-seam mining.

horizontal auger
 * A rotary drill, mechanically driven, for drilling horizontal blasting holes in quarries and opencast pits. See also: auger; vertical auger drill.

horizontal balance
 * A magnetic-field balance instrument much less commonly used than the vertical type. It is quite similar to it in construction except that the magnet points approx. vertically instead of horizontally.

horizontal borer
 * A machine, making holes from 2 to 6 in (5.08 to 15.24 cm) in diameter, used for drilling overburden at opencut coal mines. Bits are of the auger or winged types.

horizontal circle
 * The circular horizontal plate of a theodolite, accurately divided so that horizontal angles can be precisely measured.

horizontal crosscut
 * See: horizontal drive.

horizontal cut
 * See: drag cut.

horizontal-cut underhand
 * See: underhand stoping.

horizontal departure
 * The amount, expressed in feet or degrees, a borehole has digressed horizontally from the intended target.

horizontal dip slip
 * See: horizontal slip.

horizontal displacement
 * a. A term used by Tolman to designate strike slip.

b. The distance two formerly adjacent points moved horizontally. c. See: strike slip.

horizontal drive
 * An opening with a small inclination (about 2 to 4 mm for 1 m in length) in the direction toward the shaft for draining the water and to facilitate hauling of the full cars to the shaft. Syn: horizontal crosscut.

horizontal fault
 * A fault in the Earth's crust with no vertical displacement.

horizontal intensity
 * a. The intensity of the horizontal component of the magnetic field in the plane of the magnetic meridian.

b. The horizontal component of the vector magnetic-field intensity; it is one of the magnetic elements, and is symbolized by H. CF: vertical intensity.

horizontal load-bearing test
 * See: load-bearing test.

horizontal pendulum
 * A pendulum whose mass is constrained to move horizontally.

horizontal prism
 * See: macrodome.

horizontal-ring drilling
 * See: horadiam.

horizontal screens
 * Shaking screens with the plates supported in an essentially horizontal position that have been developed to obtain the advantages of low head room requirement.

horizontal separation
 * In faulting, the distance between the two parts of a disrupted unit (e.g., bed, vein, or dike), measured in any specified horizontal direction. CF: vertical separation. See: strike slip.

horizontal slip
 * In a fault, the horizontal component of the net slip. CF: vertical slip. Syn: horizontal dip slip.

horizontal takeup
 * A mechanism in which the takeup or movable pulley travels in an approx. horizontal plane.

horizontal throw
 * The heave of a fault.

hornblende granite
 * A felsic plutonic rock, generally adamellite or granodiorite, containing an amphibole (often hornblende) as an essential dark-colored constituent; with decreasing quartz it grades through tonalite into normal diorite.

hornblende schist
 * A schistose metamorphic rock consisting principally of hornblende, with little or no quartz. Unlike amphibolite, it does not need to contain plagioclase.

horn coal
 * a. Eng. Coal worked partly end-on and partly face-on.

b. A variety of cannel coal from South Wales. c. A coal that emits an odor when burning like that of burnt horn. d. Term in use in Saxony, Germany, for a variety of pitch coal similar to cannel coal. Syn: half end.

horn coral
 * Solitary coral.

hoernesite
 * See: hoernesite.

hornfels
 * A fine-grained rock composed of a mosaic of equidimensional grains without preferred orientation and typically formed by contact metamorphism. Porphyroblasts or relict phenocrysts may be present in the granoblastic matrix. See also: calc-silicate hornfels; pelitic hornfels; magnesian hornfels.

horn lead
 * See: phosgenite.

horn quicksilver
 * See: calomel.

Hornsey process
 * A method for the low-temperature reduction of iron ore by means of a series of rotary kilns. The kilns are each about 5 ft (1.5 m) in diameter and 30 ft (9.1 m) in length. The first is used for preheating, the second for reduction, and the third for cooling the product. Pulverized coal is used, which makes it readily possible to control the combustion and to maintain constant temperature.

horn silver
 * See: chlorargyrite; embolite.

horn socket
 * A fishing tool specially designed to recover lost collared drill rods or drill pipe. It consists of a smooth-wall, tapered socket, the larger end down, equipped with a spring latch, which grips the drill rod under the collar when it is slid down over the top of the lost drill rod. When the socket is equipped with a flaring (bell-shaped) mouth, it is called a bell-mouth socket.

horn tiff
 * In Missouri, calcite stained with carbonaceous material; sometimes dark enough to be mistaken for sphalerite.

horse
 * a. Any irregularity cutting out a portion of the vein. See also: rock fault.

b. To split into branches, as a vein of ore in a mine. c. Rock occupying a channel cut into a coalbed. See also: horseback. d. A body of sandstone or shale occupying a channel in a coal seam. See also: horseback. e. In structure, a large block of displaced wall rock caught along a fault, particularly a high-angle normal fault. f. A mass of country rock lying within a vein. See also: internal waste.

horseback
 * a. See: cutout; swell.

b. A bank or ridge of foreign matter in a coal seam. c. A large roll in a coal seam. d. A clay vein in a coal seam. Syn: kettleback. See also: horse; symon fault; washout; slip. e. A name applied by some writers to floor rolls in coal mines. f. Applied in some areas to clay veins; i.e., intrusions of clay into coalbeds. See also: clay vein; sandstone dike. g. Eng. A mass of stone with a slippery surface in the roof. In shape, it resembles a horse's back. h. Natural channels cut or washed away by water in a coal seam and filled up with shale and sandstone. Sometimes, a bank or ridge of foreign matter in a coal seam. i. A portion of the roof or floor that bulges or intrudes into the coal. j. A mass of country rock lying within a vein or bed. k. A piece of slate, flat underneath, thick in the middle, and running out to a thin edge upon each side. See also: kettle bottom. l. Eng. A tree branch that has been horizontally embedded, carbonized, and compressed into lenticular shape in shale immediately above a coalbed. m. A term used in Maine for a low and somewhat sharp ridge of sand or gravel; also, but not generally, a ridge of rock that rises for a short distance with a sharp edge. A hogback.

horseback excavator
 * In bituminous coal mining, one who excavates horseback (banks or ridges of dirt or rock in the coal seam) in a strip mine with a power shovel.

horseflesh ore
 * See: bornite.

horse gear
 * Bar pulled around by draft animal to actuate winding capstan. Syn: whim gin. Also called bullock gear.

horsepower applied
 * See: power upon the air.

horsepower-hour
 * The work performed or the energy consumed by working at the rate of 1 hp for 1 h (2.68 MJ), being equal to 1,980,000 ft.lbf (2.68 X 10 (super 6) N.m). Abbrev., hp.h.

horsepower of ventilation
 * The work done in ventilating a mine or part of a mine is measured by the quantity circulated multiplied by the ventilating pressure required, the quantity being measured in cubic feet per minute (cubic meters per minute) and the pressure in pounds per square foot (kilograms per square meter). The horsepower required is, therefore, this product divided by 33,000.

horsepower pull
 * The effort necessary to maintain the normal operating speed of a conveyor under a rated capacity load. To this must be added the effort of acceleration, drive losses, etc., to arrive at a final driving effort. Horsepower pull may be referred to in terms such as effective tension, chain pull, turning effort, gear tooth pressure, etc. See also: effective belt tension.

horsetail
 * Said of a major vein dividing or fraying into smaller fissures; also, said of an ore comprising a series of such veins.

horsetail ore
 * Ore in fractures that diverge from a major fracture.

horse transport
 * An old method of transportation in mines in which horses were used to pull the mine cars along the roadways. Stables were installed underground in order for the horses to be kept permanently in the mine. Horse transportation has been replaced today by mechanical transport.

horse whim
 * A device used for raising ore or water from mines, provided with radiating beams to which horses, oxen, or camels may be yoked.

horsfordite
 * A possibly isometric mineral, Cu (sub 3) Sb ; silver-white; sp gr, 8.8; reported from Lesbos Island, Greece.

horst
 * An elongate, relatively uplifted crustal unit or block that is bounded by faults on its long sides. It is a structural form and may or may not be expressed geomorphologically. Etymol: German: no direct English equivalent. CF: graben.

hortonolite
 * A magnesian variety of fayalite.

hose coupling
 * A joint between a hose and a steel pipe, or between two lengths of hose.

hoshiite
 * A nickeloan variety of magnesite.

Hoskold formula
 * Two-rate valuation formula, once much used to determine present value (Vp) of mining properties or shares, with redemption of capital invested. Largely replaced by Morkill's formula.

host
 * A rock or mineral that is older than rocks or minerals introduced into it or formed within or adjacent to it, such as a host rock, or a large crystal with inclusions of smaller crystals of a different mineral species; a palasome. Ant: guest.

host element
 * A common element that is substituted by a trace element in a rock mineral.

host rock
 * A body of rock serving as a host for other rocks or for mineral deposits; e.g., a pluton containing xenoliths, or any rock in which ore deposits occur. It is a somewhat more specific term than country rock.

hot
 * Applied to a mine or part of a mine that generates methane in considerable quantities.

hotbed
 * An area, adjacent to the runout table, where hot rolled metal is placed to cool. Sometimes called the cooling table.

hot blast
 * Air forced into a furnace after having been heated.

hot-blast man
 * A stove tender at blast furnaces.

hot-blast system
 * The plenum system of ventilation.

hot-carbonate process
 * A process developed by the U.S. Bureau of Mines in which a hot solution of potassium carbonate is used to absorb impurities from gases and is then regenerated for reuse in a continuous cycle with maximum efficiency and minimum wasted heat. Also called hot-potash process; Benfield process.

hot cell
 * A heavily shielded enclosure in which radioactive materials can be handled remotely through the use of manipulators and viewed through shielded windows so that there is no danger to personnel.

Hotchkiss superdip
 * Much more sensitive than the common dip needle. The instrument consists of a magnetic needle free to rotate about a horizontal axis and a nonmagnetic bar with a counterweight at the end which is attached to the needle at its pivot, the two axes making an angle that can be varied. It measures changes in the total field and can be used to measure variations in the vertical field if its plane is oriented in a direction perpendicular to the magnetic meridian. See also: dip needle.

hot crushing strength
 * Compressive strength of brick at high temperature.

hot-dip coating
 * The process of dipping metal components in molten tin or zinc to protect them against corrosion. See also: galvanizing.

hot-dip galvanizing
 * Immersion of iron or steel articles in a bath of melted spelter, to produce a zinc coating.

hot-drawn
 * Elongation of metal wire, tube, or rod by drawing it while heated through a constricting orifice. Opposite of cold-drawn.

hot forming
 * Working operations such as bending, drawing, forging, piercing, pressing, and heading performed above the recrystallization temperature of the metal.

hot laboratory
 * A laboratory designed for the safe handling of radioactive materials. Usually contains one or more hot cells.

hot-laid type
 * A bituminous pavement that is mixed and laid at relatively high temperatures, generally above 250 degrees F (121 degrees C). The highest type pavement that can be laid, it has greater durability and lower maintenance than any other type.

hot material
 * Any material that, at the time of charging, is at a temperature of 70 degrees C or higher.

hot-metal ladle
 * A ladle for the transfer of molten iron from a blast furnace to a mixer furnace and from there to a steel furnace; alternatively, the ladle may transfer molten pig iron direct from blast furnace to steel furnace. Such ladles are generally lined with fire clay refractories, but for severe conditions high-alumina and basic refractories have been tried with some success.

hot-metal mixer
 * A large holding furnace for molten pig iron. The capacity of these furnaces, which are of the tilting type, is up to 1,400 st (1,270 t). Hot metal mixers may be active (that is, the pig iron is partially refined while in the furnace) or inactive (that is, the pig iron is merely kept molten until it is required for transfer to a steelmaking furnace). In either case, the bottom and walls of the furnace are made of magnesite refractories and the roof of silica refractories.

hot miller
 * A tool operated by compressed air, fitted with cutting wheels that mill the hot cutting edges or rock drill bits to the required angle. See also: detachable bit.

hot-quenching
 * Quenching in a medium at an elevated temperature.

hot rolling
 * The passing of hot steel bars through pairs of steel rolls to form rolled-steel sections. The final dimension of the product is approached in stages by adjusting the height of the rolls.

hot shortness
 * Embrittlement of steel or wrought iron when hot, usually due to excessive sulfur content.

hot spot
 * a. A small portion of a furnace shell that is warmer than the rest. It indicates a thin lining.

b. The zone of highest temperature within a glass-melting furnace.

Hot Springs diamonds
 * Quartz crystals found near Hot Springs, AR.

hot top
 * A refractory-lined steel or iron casting inserted into the tip of a mold and supported at various heights to feed an ingot as it solidifies.

hot-wire anemometer
 * Instrument particularly suited to the measurement of very low air velocities and the fluctuating velocities that occur in turbulent flow. Basically, it consists of a wire or wires, usually platinum, supported in a frame and heated electrically. When exposed to an air current, the heated wire cools, and as a result, its electrical resistance alters. The heated wire forms one arm of a Wheatstone-bridge-type circuit, and measurements of resistance change may be correlated with the velocity of airflow that caused that change.

hot working
 * Deforming metal plastically at such a temperature and rate that strain hardening does not occur. The low limit of temperature is the recrystallization temperature.

hourglass structure
 * A type of zoning, esp. common in clinopyroxenes and chloritoids, in which a core, distinguished from the outer part by a difference of color or optical properties, has a cross section resembling that of an hourglass.

house
 * a. Corn. A large mass of rich tin ore. Also called a carbona.

b. Eng. See: gunnie; turnhouse.

house coal
 * Coal for use around colliery in miners' houses and for local sale.

house of water
 * Corn. A cavity or space filled with water.

hove
 * a. Scot. Past participle of heave. The floor of a mine working is said to heave or rise.

b. A lode is hove or thrown in a certain direction by a fault.

hovel
 * A large conical or conoidal brick structure within which a firing kiln is built.

howell
 * The upper stage in a porcelain furnace.

howlite
 * A monoclinic mineral, Ca (sub 2) B (sub 5) SiO (sub 9) (OH) (sub 5) ; white; earthy or in small nodules; in the Mojave Desert region of California.

H-piece
 * That part of a plunger lift in which the valves or clacks are fixed.

HQ
 * A letter name specifying the dimensions of bits, core barrels, and drill rods in the H-size and Q-group wireline diamond drilling system having a core diameter of 63.5 mm and a hole diameter of 96 mm.

hsianghualite
 * An isometric mineral, Ca (sub 3) Li (sub 2) Be (sub 3) (SiO (sub 4) ) (sub 3) F (sub 2) ; occurs with taaffeite in metamorphosed limestone in Hunan Province, China.

huanghoite
 * A trigonal mineral, BaCe(CO (sub 3) ) (sub 2) F ; as yellow platy masses in hydrothermal deposits near the Huang-Ho River, China. Also spelled huangeite-(Ce).

huascolite
 * A variety of galena in which part of the lead is replaced by zinc.

hub
 * A survey point marked with a stake or metal pin and used as a reference point for locating a specific spot in a predetermined direction.

hub-and-groove diameter
 * The outside diameter of the hub, or the diameter at the base of a groove cut in the hub to provide clearance for the link plates.

Hubbard distributor
 * stone dust. Resting on the surface of the stone dust is a steel plate 1/4 in (0.64 cm) in thickness fitting loosely into the box and perforated with holes 3/16 in (0.48 cm) in diameter. The plate is connected by a series of chains and levers to a lever between the rails on either the loaded or empty side of the roadway. Each tub passing along depresses the lever and causes the steel plate to be lifted. A counterweight restores the track lever to vertical and the plate falls, causing a puff of stone dust to be ejected through each hole into the ventilating current. Thus stone dusting keeps pace with output.

huebnerite
 * A monoclinic mineral, 2[MnWO (sub 4) ], with Mn replaced by Fe toward ferberite in the series commonly known as wolframite; one perfect cleavage; resinous; sp gr, 7.12; in granitic rocks, including pegmatites; in high-temperature quartz veins, and in placers; may be alone or associated with cassiterite, or with sulfides of iron, lead, or zinc. Also spelled huebernite. See also: sanmartinite; huebnerite.

hudge
 * a. A small box or tram without wheels, running on timber slides, drawn by a boy, in thin and steep seams.

b. An iron bucket for hoisting ore or coal. See: bowk.

huebnerite
 * A brownish-red tungstate of manganese, Mn (super +2) WO (sub 4), one of the end-members of a variable series, commonly known as wolfram or wolframite, (Fe, Mn)WO (sub 4) ; monoclinic. Syn: huebnerite; wolframite.

huel
 * Corn. A mine; a variant of wheal.

Huff separator
 * Type of electrostatic separator used in ore treatment.

hugger
 * a. N. of Eng. In coal mining, a back or cleat.

b. Northumb. The principal cleat in coal. See also: backs.

hugger belt conveyor
 * Two belt conveyors whose conveying surfaces combine to convey loads up steep inclines or vertically.

hugger drive
 * A drive employing an auxiliary belt that bears against the surface of the conveying belt as it passes around the drive pulley to increase the pressure between the conveyor belt and the drive pulley.

hulk
 * a. Corn. To take down and remove the softer part of a lode, before removing the harder part. See also: gouge.

b. The removal of the soft gouge. c. The excavation made by this operation.

Hull cell
 * A special electrodeposition cell giving a range of known current densities for test work.

hulsite
 * A monoclinic mineral, (Fe,Mg) (sub 2) (Fe,Sn)BO (sub 5) ; forms small black crystals or tabular masses at the contact of granite and metamorphosed limestone.

humacite
 * A group name for bitumens that vary from gelatinous to hard resinous or elastic. Believed to represent an emulsion of highly acidic (humic acids) hydrocarbons with a varying amount of water (as high as 90%). Insoluble in organic solvents.

humboldtine
 * A hydrous ferrous oxalate, Fe (super 2+) C (sub 2) O (sub 4) 2H (sub 2) O, occurring in capillary or botryoidal forms and black shale. Syn: humboltite; oxalite.

humboldtite
 * See: datolite; humboldtine.

Humboldt jig
 * Movable-screen type of ore jig.

humboltite
 * See: datolite; humboldtine.

humic acid
 * Black acidic organic matter extracted from soils, low-rank coals, and other decayed plant substances by alkalis. It is insoluble in acids and organic solvents.

humic coals
 * a. A group of coals, including the ordinary bituminous varieties, that have been formed from accumulations of vegetable debris that have maintained their morphological organization with little decay. The majority of them are banded and have a tendency to develop jointing or cleat. Chemically, humic coals are characterized by hydrogen varying between 4% to 6%.

b. Coals in which the attritus may be composed predominately of transparent humic degradation matter. c. Introduced in 1906 by H. Potonie to describe coals, the original organic matter of which underwent change chiefly by humification; i.e., through the process of peat formation in the presence of oxygen. Most seams of coal consist principally of humic coal and the technological properties vary with their rank, with their petrographic composition, and with the manner of distribution of mineral inclusions.

humic degradation matter
 * Finely comminuted degradation matter in coal, largely but not altogether derived from the woody tissues of plants, and like anthraxylon, largely derived from lignin.

humid heat
 * Ratio of the increase in total heat per kilogram of dry air to the rise in temperature, with constant pressure and humidity ratio.

humidifying effect
 * The quantity of water evaporated per unit of time (usually 1 h) times the latent heat of vaporization at the evaporating temperature.

humidity
 * The water-vapor content of the atmosphere. The unmodified term often signifies relative humidity. See also: absolute humidity; specific humidity.

humidostat
 * An instrument for regulating the humidity in the atmosphere. Syn: hygrostat.

humins
 * In coal, amorphous brown to black substances formed by natural decomposition from vegetable substances; insoluble in alkali carbonates, water, and benzol.

humite
 * The mineral group alleghanyite, chondrodite, clinohumite, humite, jerrygibbsite, leucophoenicite, manganhumite, norbergite, ribbeite, and sonolite; monoclinic and orthorhombic fluosilicates of magnesium, iron, and/or manganese, with hydroxyl commonly replacing fluorine; similar physical properties, and structures closely related to those of the olivines; in metamorphosed dolomitic limestones, or skarns associated with ore deposits; commonly as chondrodite and clinohumite; at the Tilly Foster iron mine near Brewster and at Franklin, NJ.

humite group
 * A group of isomorphous minerals consisting of olivine, chondrodite, humite, and clinohumite, and closely resembling one another in chemical composition, physical properties, and crystallization.

Hummer screen
 * Screen used to size moderately small material, vibrated electrically by solenoid action.

humocoll
 * Peat derived from humic material and in rank corresponding to saprocoll.

humonigritite
 * A type of nigritite that occurs in sediments. CF: polynigritite; keronigritite.

humopel
 * An organic mud composed of humic material corresponding in rank to sapropel.

humosite
 * A microscopical constituent of torbanite; translucent; dark brownish-red; isotropic. See also: gelosite; matrosite; retinosite.

humper
 * See: booster conveyor.

Humphrey's spiral
 * A concentrating device that exploits differential densities of coal and its associated impurities by a combination of sluicing and centrifugal action. The material gravitates down through a stationary spiral trough with six turns (five for ore treatment) of mean radius 8 in (20.32 cm) with a fall per turn of 11 in (27.94 cm). Heavy particles stay on the inside, the lightest ones climb to the outside, and the resulting bands are separated at convenient points.

humus
 * Dark-colored, organic, well-decomposed soil material consisting of the residues of plant and animal materials together with synthesized cell substances of soil organisms and various inorganic elements.

humus coal
 * a. Coal composed of anthraxylon in varying proportions and of varying thicknesses, associated with transparent attritus.

b. Amorphous brown to black coal formed from vegetable matter and insoluble under continuous boiling in caustic alkalies; also insoluble in water and benzol.

hundredweight
 * A weight commonly reckoned in the United States, and for many articles in England, at 100 avoirdupois lb, but commonly in England, and formerly in the United States, at 112 avoirdupois lb. There is also an older hundredweight, called the long hundredweight, of 120 avoirdupois lb. Abbrev., cwt.

Hungarian cat's eye
 * An inferior greenish cat's eye obtained in the Fichtelgebirge in Bavaria. No such stone occurs in Hungary.

Hungarian mill
 * A rotating, grinding mill used in Hungary for removing small portions of gold from quartz by mixing with mercury; one of the many forms of pan amalgamators.

Hungarian opal
 * a. A white opal, with a fine color play; found in Slovakia.

b. A name used by the importing trade for any white opal regardless of origin.

Hungarian riffles
 * Riffles used in undercurrents that are small angle irons or pieces of wood shod with iron. Syn: transverse riffles.

hung fire
 * Delay in a blasting explosion caused by dampness of the powder or by too slow combustion of the fuse.

hungry
 * a. Said of a rock, lode, or belt of country that is barren of ore minerals or of geologic indications of ore, or that contains very low-grade ore. Ant: likely.

b. Said of a soil that is poor or not fertile.

hung shot
 * a. A shot that does not explode immediately upon detonation or ignition. See also: hangfire.

b. A delayed shot.

Hunt and Douglas process
 * Consists of roasting matte carrying copper, lead, gold, and silver at a very low temperature, forming copper sulfate and oxide, but not silver sulfate. This product is leached with dilute sulfuric acid for copper. The resulting solution is treated with calcium chloride, and the copper is precipitated as subchloride by passing SO (sub 2) through the solution. The cuprous chloride is then reduced to cuprous oxide by milk of lime, regenerating calcium chloride, and the cuprous oxide is smelted.

huntilite
 * A silver arsenide occurring with native silver at Silver Islet, Lake Superior, MI.

hunting
 * a. Unstable conditions occur with all fans when they are working against too high a resistance, and with forward-bladed radial-flow fans over most of their range, including the point of maximum efficiency. In these conditions, a drop in volume causes only a slight rise in fan pressure and conditions are only slowly restored to normal. This leads to continual and heavy fluctuations in load, a phenomenon known as "hunting." In extreme cases, a fan may hunt to the point where there is no rise in pressure with decreasing volume. It can then lose its load entirely and never recover it.

b. Abnormal time lag in automatic control system, in which a corrective change is so much exceeded that overmodulation ensues, the result being oscillation above and below the desired norm. Also called cycling; oscillation.

hunting coal
 * York. Ribs and posts of coal left for second working.

Huntington-Heberlein process
 * A sink-float process employing a galena medium and utilizing froth flotation as the means of medium recovery.

Huntington mill
 * A cylindrical vertical tub from 3-1/2 to 6 ft (1.07 to 1.83 m) in diameter, with screen-guarded peripheral apertures through which ore pulp can be discharged after passing through the comminuting zone. Grinding is done by four rolling mullers, which hang inside from a yoke and which press outward when rotating, thus bearing an ore caught between them and the inner wall of the tub. Syn: pendulum mill.

hunting tooth
 * Extra tooth designed for driven wheel so that its total number of teeth is not a multiple of those of the driving pinion.

huntite
 * A trigonal mineral, CaMg (sub 3) (CO (sub 3) ) (sub 4) ; in white chalky masses in caves; as a weathering product in vugs and veins in magnesium-rich rocks; in magnesite deposits in Nevada.

Hunt's process
 * Treatment of precious metal ores containing copper or zinc, using an ammoniacal cyanide solution and recovering ammonia by boiling.

hurdle
 * A temporary screen or curtain to deflect the air upwards against the roof to disperse gas.

hurdle screen
 * a. Scot. A temporary screen or curtain for clearing gas out of a pit. Used esp. where gas has collected in potholes or caves in the roof.

b. Scot. A screen used in underground firefighting that pushes the smoke back toward the fire and allows the firefighting team to advance within striking distance of the fire.

hurdle sheet
 * A screen of brattice cloth erected across a roadway below a roof cavity or at the ripping lip to divert the air current upwards to dilute and remove an accumulation of combustible gases. See also: pocket of gas.

hurdy-gurdy
 * a. See: hurdy-gurdy wheel.

b. A dance house in a mining camp.

hurdy-gurdy drill
 * A hand auger used to drill boreholes in soft rock or rock material, such as soil, clay, coal, etc.

hurdy-gurdy wheel
 * A water wheel operated by the direct impact of a stream upon its radialIy placed paddles. Syn: hurdy-gurdy.

hureaulite
 * A monoclinic mineral, Mn (sub 5) (PO (sub 4) ) (sub 2) [PO (sub 3) (OH)] (sub 2) .4H (sub 2) O ; in pegmatites.

hurlbarrow
 * Scot. A wheelbarrow.

hurricane air stemmer
 * A mechanical device for the rapid stemming of shotholes. It consists of a sand funnel connected by a T-piece to the charge tube, one end of which is provided with a valve and fittings to the compressed air column. The funnel is filled with sand, which is held uppermost, and the charge tube is inserted into the shothole. The sand is injected by the compressed air, and the tube is gradually withdrawn as the hole is being filled.

hurry
 * a. Scot. A screen or sieve.

b. To haul, pull, or push cars of coal in a mine. c. A chute, slide, or pass as for ore in a mine, or for coal discharged from cars into vessels. d. Gr. Brit. A wooden staging on a navigable river from which to load vessels with coal.

hurry gum
 * Scot. The fine material that passes through a screen or sieve.

hush
 * Eng. To clear away (soil) from ore with a rush of water.

hushing
 * See: hydraulic prospecting; booming.

hutch
 * a. Corn. A cistern or box for washing ore. See also: jig. Syn: washing hutch.

b. Scot. A basket for coal. c. The bottom compartment of a coal or ore-dressing jig. d. The part of a jig below the screen plate, in which the washbox rests and the pulsating movement of the water takes place. e. A car on low wheels in which coal is drawn and hoisted out of a mine pit. f. To wash ore in a box or jig. g. A basket for measurement and transport of coal. h. A small train or wagon for removing coal or ore from a mine. i. An old and varying English measure, as (for coal) 2 Winchester bushels (70.5 L). j. Scot. Two hundredweight (91 kg or 96 kg) of pyrites. k. The bottom compartment of an ore-dressing jig and/or the mineral product that collects there. l. The part of a washbox situated below the screenplate in which the controlled pulsating movement of the water takes place.

hutch cleading
 * The boards that form the sides, bottom, and ends of a mine car, or hutch.

hutcher
 * One who runs hutches.

hutching
 * N. of Eng. Term used for tramming.

hutch mender
 * A repairer of tubs or hutches broken in a mine.

hutch mounting
 * Scot. The ironwork on the frame and box of a wooden hutch.

hutch product
 * The fine, heavy materials that pass through the meshes of the screen in a jig.

hutch road
 * a. A road through a mine.

b. Scot. A hutch tramway.

hutchwork
 * In mineral processing, the concentrates passing down through the ore jig into the hutch.

huttonite
 * A very rare, strongly radioactive, colorless to pale cream, monoclinic mineral, ThSiO (sub 4), found in sands and gravels with scheelite, cassiterite, uranothorite, zircon, ilmenite, and gold.

Huwood loader
 * This machine comprises a number of horizontal rotating flight bars working near the floor of the seam and driven through gearing by an electric motor. These bars push into the coal in their extended position and are almost completely concealed inside the loader casing in their retracted position. They push prepared coal up a ramp on to a low, bottom-loaded conveyor belt. The machine is hauled along the face by means of two steel ropes wound on separate drums on the loader; one rope passes up the front of the coal and is held by means of an anchor prop; the other rope is threaded under the cut coal by means of a threader pipe attached to the rear of the coal cutter. Lengths of rope equal to the drum capacity are joined by figure-8 links and are detached and unwound from the drum as the loader proceeds along the face.

Huwood slicer
 * A cutter-loader based on the plow principle and designed to cut coal that is too hard for the ordinary plow. Two vertical blades, fitted one at each end of the machine, carry cutting picks that shear the coal from the face by an oscillating motion. The machine is hauled backward and forward along the face by a chain haulage mounted on the tail end of the conveyor. The conveyor and slicer are held up to the coal by pneumatic rams spaced along the goaf side of the conveyor. The sheared coal is forced from the face by the wedge shape of the machine and is loaded on to the armored conveyor by means of specially shaped ramps. The machine has been designed for seams with a minimum thickness of 4 ft (1.22 m) and has a maximum cutting depth of 14 in (35.56 cm). Syn: activated plow.

Huygen's principle
 * A very general principle applying to all forms of wave motion that states that every point on the instantaneous position of an advancing phase front (wave front) may be regarded as a source of secondary spherical wavelets. The position of the phase front a moment later is then determined as the envelope of all of the secondary wavelets (ad infinitum). This principle is useful in understanding effects due to refraction, reflection, diffraction, and scattering, of all types of radiation, including sonic radiation as well as electromagnetic radiation, and applying also to ocean wave propagation.

HW
 * Letter name specifying the dimensions of bits, core barrels, and drill rods in the H-size and W-group wireline diamond drilling system having a core diameter of 76.2 mm and a hole diameter of 99.2 mm. Syn: HX.

H wave
 * See: hydrodynamic wave.

HX
 * Letter name specifying the dimensions of core, core barrels, and casing in the H-size and X-series wireline diamond drilling system having a core diameter of 76.2 mm and a hole diameter of 99.2 mm. The HX designation for coring bits has been replaced by the HW designation. Syn: HW.

hyacinth
 * A red-orange variety of zircon; also applied to similarly colored garnet, quartz, and other minerals. Syn: cinnamon stone; essonite; jacinth.

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