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Appendix:Dictionary of Mining, Mineral, and Related Terms/R/1

rabatage
 * A system of working steep seams of any thickness.

rabbit-eye
 * York. Limestone in the Coralline Oolite. CF: toad's-eye.

rabbittite
 * A monoclinic mineral, Ca (sub 3) Mg (sub 3) (UO (sub 2) ) (sub 2) (CO (sub 3) ) (sub 6) (OH) (sub 4) .18H (sub 2) O ; radioactive; forms yellow efflorescence on mine walls.

rabble
 * a. An iron scraper serving as a rake in removing scoriae from the surface of melted metal.

b. A charcoal burner's shovel. c. A mechanical rake for skimming the bath in a melting or refining furnace or for stirring the ore in a roasting furnace by hand or mechanically.

rabbler
 * a. See: rabble.

b. One who uses a rabble, as in puddling iron. c. A scraper.

rabbling
 * Stirring molten metal, ore, or other charge, using a hoelike tool or other device.

rabbling tool
 * A rabble of simple construction for use by hand. Also called rabble rake. See also: rabble.

race
 * A small thread of spar or ore.

raceway
 * The term is applied to conduits, moldings, and other hollow material, often concealed, through which wires are fished from one outlet to another.

rack
 * a. An inclined trough for washing or separating ore.

b. A toothed or notched drill-base-slide and meshing-gear pinion used to facilitate the moving of a drill to clear the borehole when hoisting or lowering the drill string; generally limited to larger, skid-mounted machines. c. A framework of wood or metal for the orderly storage of core, pipe rods, etc., in a horizontal position. d. A tilting table on which concentrates are separated from the passing flow of finely ground pulp, the system being arranged to be periodically self-flushing. e. A screen composed of parallel bars to catch floating debris. f. In electroplating, a frame used for suspending and conducting current to one or more cathodes during electrodeposition.

rack-a-rock
 * Mining explosive based on a mixture of potassium chlorate and nitrobenzene.

rack back
 * To move a drilling machine away from the borehole collar by sliding it on its base, using the rack-and-gear pinion to facilitate moving the machine. See also: rack.

racked timbering
 * Timbering braced diagonally as stiffening against deformation.

rack frame
 * Inclined table used to treat slimes.

rack gear
 * A toothed bar.

racking
 * a. Old term for concentration in sluice boxes.

b. The process of separating ores by washing on an inclined plane. c. See: ragging.

racking table
 * A table on which to wash ore slimes. See also: rack.

rack railroad
 * A cog railway; cog tramway.

rack up
 * a. To move the drilling machine forward into alignment with the borehole, using the rack-and-gear pinion to facilitate moving the machine.

b. To stack and arrange the drill rods in an orderly fashion in the tripod, mast, or derrick, or horizontally on a rack provided on the ground. c. To place core on a rack.

radial
 * Said of lines or other linear phenomena converging at a single center or departing from one.

radial arm
 * The movable cantilever supporting the drilling saddle in a radial drilling machine.

radial axis
 * See: longitudinal trace.

radial dikes
 * A descriptive term for dikes that radiate outward from a center, commonly a volcanic neck or stock.

radial drainage pattern
 * A drainage pattern in which consequent streams radiate or diverge outward, like the spokes of a wheel, from a high central area; it is best developed on the slopes of a young, unbreached domal structure or of a volcanic cone.

radial drill
 * a. A heavy drilling machine in which the drilling head is capable of radial adjustment along a rigid horizontal arm carried by a stand. See also: radial percussive coal cutter.

b. A small diamond drill having a drilling head that can be adjusted radially along a rigid horizontal arm radiating from a vertical column; usually driven by air and used to drill radial blastholes underground. See also: radial drilling.

radial drilling
 * The drilling of a number of holes in a single plane and radiating from a common point. CF: horadiam.

radial-flow fan
 * A mine fan in which the air enters along the axis parallel to the shaft and is turned through a right angle by the blades and discharged radially. There are three main types with (1) backwardly inclined blades; (2) radial blades; and (3) forward curved blades. In (2) and (3) the blades are made of sheet steel, while in (1) the present tendency is to replace curved sheet-steel blades by blades of aerofoil cross section. The aerofoil bladed radial-flow fan has an efficiency of about 90%. CF: axial-flow fan; mixed-flow fan.

radial machineman
 * In bituminous coal mining, a person who operates a radial-type coal cutter. The machine remains stationary at the center of the working place and undercuts or shears the coal in an arc rather than making a straight cut by moving across the working face. Also called arcwall machineman.

radial percussive coal cutter
 * A heavy coal cutter for use in headings and rooms in pillar methods of working. The machine weighs about 12 hundredweight (545 kg) and is usually mounted on a light carriage to suit the mine track. A percussive drill, with extension rods, makes a horizontal cut about 5-1/2 ft (1.68 m) deep and 15 ft (4.57 m) wide at any height in the heading. The central column is tightened between roof and floor about 4-1/2 ft (1.37 m) from the face. The machine can also be used for drilling shotfiring holes.

radial pressure
 * The radial pressure of wire rope is a function of the rope tension, rope diameter, and tread diameter. The radial pressure can be determined by the following equation: P = 2T/Dd, where P equals radial pressure in pounds per square inch; T equals rope tension in pounds; D equals tread diameter of sheave or drum in inches; and d equals rope diameter in inches.

radial slicing
 * A method of caving by which all the ground around a central raise might be worked in a series of slices arranged like the spokes of a wheel.

radial strain
 * The change in length per unit length in a direction radially outward from the charge.

radial stress
 * a. Stress normal to the tangent to the boundary of any opening.

b. In the Earth, the stress normal to a spherical surface.

radial velocity
 * In a fan, the quantity of air delivered in cubic meters per second divided by the outlet area of the fan at the periphery.

radial ventilation
 * A ventilation system in which a number of downcast shafts arranged around the periphery of the working area are served by a common upcast shaft within the area, or vice versa. Sometimes known as compound ventilation.

radian
 * A unit of plane angular measurement equal to the angle at the center of a circle subtended by an arc equal in length to the radius. One radian equals about 57.29 degrees.

radiant energy
 * Energy that radiates or travels outward in all directions from a source.

radiated
 * Said of an aggregate of acicular crystals that radiate from a central point. CF: spherulitic.

radiated pyrite
 * See: marcasite.

radiating
 * A mineral with crystals or fibers arranged around a center point, for example, stibnite. Also called divergent.

radiation absorbed dose
 * The basic unit of absorbed dose of ionizing radiation. One radiation absorbed dose (abbrev., rad) equals the absorption of 100 ergs of radiation energy per gram of matter.

radiation damage
 * a. A general term for the alteration of properties of a material arising from exposure to X-rays, gamma rays, neutrons, heavy-particle radiation, or fission fragments in nuclear fuel material.

b. Damage done to a crystal lattice (or glass) by passage of fission particles or alpha particles from the nuclear decay of a radioactive element residing in or near the lattice. See also: metamict mineral.

radiation log
 * A device used either on the surface or in drill holes to detect and/or indicate the occurrence or the nearby presence of radioactive minerals. Also called electronic logger; gamma-ray detector; Geiger counter; Geiger-Mueller counter; Geiger-Mueller probe; scintillation counter; scintillometer. �M  �]f L`f ��?��       � 2 DICTIONARY TERMS:radiation log See: radioactivity log. See: radioactivity log.

radiation pyrometer
 * a. A device for ascertaining the temperature of a distant source of heat, such as a furnace. A concentrated group of thermocouples, called a thermopile, is used. Radiant heat from the furnace or object is focused by a lens onto the thermopile. Radiation pyrometers may be used for measuring temperatures to 7,000 degrees F (3,870 degrees C). The device is used in automatic control systems in mineral dressing and other processes.

b. Pyrometer that determines temperature by measuring the intensity of radiation from the hot body.

radiation survey
 * A study of factors in any process or device involving radiation that could cause danger to any persons working near the process or device.

radiation-type gage
 * An instrument for measuring the density or percentage of solids in slurries flowing through pipes. It normally uses a gamma-ray source, usually cesium-137 or cobalt-60, mounted in a lead-shielded holder on one side of the pipe. A radiation detector is mounted on the opposite side. Since the absorption of the gamma radiation, as it passes through the slurry, varies as a function of the density of the slurry, the change in radiation received by the radiation detector is representative of the specific gravity or percentage of solids in the slurry. See also: differential pressure flowmeter.

radioactive
 * a. Generally, the property possessed by certain elements, such as uranium, of spontaneously emitting alpha, beta, and/or gamma rays by the disintegration of the nuclei of their atoms.

b. Of, relating to, caused by, or exhibiting radioactivity. Abbrev., RA.

radioactive decay
 * a. The change of one element to another by the emission of charged particles from the nuclei of its atoms.

b. The spontaneous disintegration of the atoms of certain nuclides into new nuclides, which may be stable or undergo further decay until a stable nuclide is finally created. Radioactive decay involves the emission of alpha particles, beta particles, and other energetic particles, and usually is accompanied by emission of gamma rays and by atomic de-excitation phenomena. It always results in the generation of heat. Syn: radioactive disintegration.

radioactive disintegration
 * See: radioactive decay.

radioactive dusts
 * Dusts that are injurious because of radiation. They include ores of uranium, radium, and thorium.

radioactive element
 * Applied to certain unstable atoms, the nuclei of which spontaneously disintegrate, emitting particles and rays, eventually reverting through a series of such emissions into an atom having a stable nucleus and a different atomic number. Radium, e.g., becomes lead-207.

radioactive mineral
 * One of six radioactive elements that occur naturally: potassium, rubidium, thorium, uranium, and associated radium, samarium, and lutecium. Thorium commonly occurs in monazite, a sparsely scattered accessory mineral of certain granites, gneisses, and pegmatites. It is concentrated, however, by weathering processes in sands and gravels as commercial placer deposits along rivers and beaches. The most important primary uranium ore minerals are davidite and uraninite, esp. pitchblende, the massive variety. These minerals are of rather underspread occurrence in certain granites and pegmatites and occur as secondary minerals in metallic vein deposits. The secondary uranium minerals, however, are more underspread and more numerous than the primary uranium ore minerals. Secondary uranium minerals are found in weathered and oxidized zones of primary deposits and, also, in irregular flat-lying sandstones, such as those in the Colorado Plateau, where the uranium mineralization was precipitated from solutions. Carnotite, the potassium uranium vanadate of conspicuous yellow color, is perhaps the most important of the secondary uranium ore minerals. Others are tyuyamunite, which is closely related to carnotite, and the torbernites and autunites which are uranium minerals.

radioactive series
 * A succession of nuclides, each of which transforms by radioactive disintegration into the next until a stable nuclide results. The first member is called the parent, the intermediate members are called daughters, and the final stable member is called the end-product. Four radioactive series are the uranium series, the thorium series, the actinium series, and the neptunium series.

radioactive tracer element
 * A radioactive isotope of an element used to study a process by observing the intensity of radioactivity.

radioactive waste
 * Equipment and materials from nuclear operations that are radioactive and for which there is no further use. Wastes are generally referred to as high-level (having radioactivity concentrations of hundreds to thousands of curies per gallon or per cubic foot); low-level (in the range of 1 microcurie per gallon or per cubic foot); and intermediate (between these extremes).

radioactivity
 * The spontaneous decay or disintegration of an unstable atomic nucleus, accompanied by the emission of radiation. See also: radioactive decay.

radioactivity log
 * a. A log of a borehole obtained through the use of gamma, neutron, or other radioactivity logging methods.

b. The generic name for well logs whose curves derive from reactions of atomic nuclei involving the behavior of gamma rays and/or neutrons. Except for the natural gamma-ray log and the spectral gamma-ray log, they record the response of rocks very near the well bore to bombardment by gamma rays or neutrons from a source in the logging sonde. Most can be obtained in cased, empty, or fluid-filled well bores. Varieties include: density log; neutron log; neutron-activation log; epithermal-neutron log; pulsed-neutron-capture log. Syn: radiation log; nuclear log. See also: gamma-ray well log; spectral gamma-ray log; neutron log.

radioactivity prospecting
 * Exploration for radioactive minerals utilizing various instruments, generally a Geiger counter or scintillation counter, by measuring the natural radioactivity of earth materials.

radioaltimeter
 * Equipment carried in survey aircraft to ensure constant height above ground (not sea) level of 300 ft or 500 ft (91.4 m or 152.4 m)--a critical factor in certain airborne geophysical prospecting and aerial mapping surveys. See also: profile flying.

radiocarbon
 * Radioactive carbon, esp. carbon-14, but also carbon-10 and carbon-11.

radiocarbon dating
 * See: carbon-14 dating.

radiochemistry
 * The chemical study of artificial and naturally occurring radioactive materials and their behavior. It includes their use in tracer studies and other chemical problems.

radioelement
 * A form or sample of an element containing one or more radioactive isotopes.

radiogenic
 * Produced by radioactive transformation. Thus, uranium minerals contain radiogenic lead and radiogenic helium. The heat produced within the earth by the disintegration of radioactive nuclides is radiogenic heat.

radiograph
 * a. A photographic shadow image resulting from uneven absorption of radiation in the object being subjected to penetrating radiation.

b. A picture produced upon a sensitive surface (such as a photographic film), by a form of radiation other than light; specif., an X-ray or a gamma-ray photograph. See: roentgenogram.

radiography
 * a. A nondestructive method of internal examination in which metal or other objects are exposed to a beam of X-ray or gamma radiation. Differences in thickness, density, or absorption caused by internal discontinuities are apparent in the shadow image either on a fluorescent screen or on a photographic film placed behind the objects.

b. The use of penetrating ionizing radiation to examine solid material. When the source of radiation is internal, such as an implanted radioactive tracer, the technique is known as autoradiography.

radiohalo
 * See: pleochroic halo.

radioisotope
 * a. An unstable isotope of an element that decays or disintegrates spontaneously, emitting radiation.

b. Radioisotope is loosely used as a syn. for radionuclide. See also: radium; radon. Syn: unstable isotope.

Radiolaria
 * a. Subclass of the Sarcodina consisting of marine protozoans that possess complex internal siliceous skeletons.

b. Silica rock formers.

radiolarian ooze
 * Deposits of siliceous ooze made up largely of radiolarian skeletons and are formed at depths between 13,000 ft and 25,000 ft (4.0 km and 7.6 km).

radio link
 * Radio signal unit used to control or communicate between scattered sections of mine, or to link isolated camp with other places.

radiolite
 * A spherulite composed of radially arrayed acicular crystals.

radiolite survey instrument
 * A one-shot bore-hole-surveying instrument having the horizontal (compass) and vertical indicator markings painted with a radioactive substance, such as that on the luminous dial of a watch. The positions of these markings are recorded on small, circular, photographic film.

radiolitic
 * a. Said of the texture of an igneous rock characterized by radial, fanlike groupings of acicular crystals, resembling sectors of spherulites.

b. Said of limestones in which the components radiate from central points, with the cement comprising less than 50% of the total rock.

radiometallography
 * The application of X-rays to the study of the internal structure of various materials, esp. metals.

radiometer
 * Essentially a heat-flow meter used to measure long-wave radiation as well as solar radiation. It can be used both for daytime and nighttime measurements and to measure the net heat transfer through a surface.

radiometric assay
 * A test to determine contained quantity of uranium. The actual uranium present may be more or less than the assay shows. See also: equilibrium; inequilibrium.

radiometric ore sorter
 * A device for separating gangue from uranium-bearing ore, after primary crushing.

radiometric prospecting
 * Use of portable Geiger-Muller apparatus for field detection of emission count in search for radioactive minerals.

radiophone
 * An FM apparatus, using the mine haulageway trolley wire for power and antenna, that permits the dispatcher to talk back and forth with his motor crews as they are moving throughout the mine. This saves stopping and starting trips to make telephone calls.

radiophyllite
 * See: zeophyllite.

radiore method
 * An electromagnetic method used in mineral exploration in which a high-frequency current is used, ranging from 30,000 to 50,000 Hz, but, if necessary, a frequency as low as 50 to 3,000 Hz, can be made available. The detecting or direction-finding coil, mounted on a tripod, has the form of a pair of spectacles and is equipped with an amplifier and head telephone. When the exciting coil is energized, a current is caused to flow in the conductor and a secondary electromagnetic field is set up around the conductor. The detecting coil is affected by both the primary field from the exciting coil and the secondary field.

radium
 * A radioactive metallic element; one of the alkaline-earth metals. Symbol, Ra. It occurs in pitchblende ore, in carnotite sands, and in all uranium minerals. See also: radioisotope.

radium G
 * A name for lead-206, the stable end-product of the radioactive disintegration of uranium-238 in the uranium disintegration series. Natural lead contains 23.6% of lead-206. Symbol, RaG. Syn: uranium-lead.

radiumite
 * A mixture of black pitchblende, yellow uranotile, and orange gummite.

radius
 * Horizontal distance from the center of rotation of a crane to its hoisting hook.

radius of curve
 * A term used in laying mine track; the calculated radius of an arc that will connect two pieces of track (at a desired angle of direction from each other) with a smooth curve section.

radius of gyration
 * The value used when calculating the slenderness ratio of pillars and struts. If A is the cross-sectional area in inches of the pillar or strut and I is its moment of inertia, the radius of gyration is (I/A), generally known as K.

radius of rupture
 * In crater tests, the average distance from the center of the explosive charge to the periphery of the crater at the surface.

radius ratio
 * a. The ratio of the radius of the smaller ion to that of the larger ion. It may not exceed 1.

b. The ratio of the radius of the smaller ion to that of the larger; commonly cation to anion. Radius ratios are used to predict coordination numbers of anions about cations in ionic crystal structures. CF: Pauling's rules.

radon
 * a. A heavy, radioactive, gaseous element; inert; the heaviest known gas. Symbol, Rn. Formed by the disintegration of uranium. Used similarly to radium in medicine. Radon build-up is a health consideration in uranium mines.

b. Heaviest known gas. Colorless as a gas; yellow to orange-red, phosphorescent, opaque crystals; sp gr of liquid, 4.4 (at -62 degrees C); and of solid, 4.0; soluble in water; and slightly soluble in alcohol and in organic liquids. All 18 known isotopes from radon-204 to radon-224 are radioactive. Radon-222 emanates from thorium; half-life, 54.5 s; and an alpha particle emitter; and radon-219 or actinon emanates from actinium; half-life, 3.92 s; and an alpha particle and a gamma ray emitter. One part of radon exists in 1 sextillion parts of air.

radon daughter
 * A radioactive element produced in the disintegration of radon. Syn: radon progeny.

radon progeny
 * The short-lived decay products of radon, an inert gas that is one of the natural decay products of uranium. The short-lived radon progeny (i.e., polonium-210, lead-214, bismuth-214, and polonium-214) are solids and exist in air as free ions or as ions attached to dust particles. The U.S. Mine Safety and Health Administration has established radiation protection standards that limit a miner's radon progeny exposure to a concentration of 1.0 WL and an annual cumulative exposure to 4 WLM. Each WLM is determined as a 173-h cumulative, time weighted exposure. Syn: radon daughter.

raffinate
 * The aqueous solution remaining after the metal has been extracted by the solvent; the tailing of the solvent extraction system.

raft
 * See: float coal.

rafter timbering
 * A method of mine timbering in which the timbers appear like roof rafters.

rafting
 * a. The transporting of sediment, rocks, silt, and other matter of land origin out to sea by ice, logs, etc., with subsequent deposition of the rafted matter when the carrying agent disintegrates.

b. Matting or agglomerating of powdered coal.

rag
 * a. In British usage, any of various hard, coarse, rubbly, or shelly rocks that weather with a rough irregular surface; e.g. a flaggy sandstone or limestone used as a building stone. The term appears in certain British stratigraphic names, as the Kentish Rag (a Cretaceous sandy limestone in East Kent). Syn: ragstone.

b. Any of various hard rocks, as a quartzose mica schist used for whetstones or a hard limestone used in building. c. A large roofing slate left rough on one side. d. To break (ore) into lumps for sorting; to cut or dress roughly (as a grindstone).

ragged rolls
 * Rolls with rough surfaces to facilitate the gripping of the steel in the first stages of rolling, as distinguished from the smooth-finishing rolls.

ragging
 * a. The rough washing or concentration of ore or slimes on a rag frame.

b. In roll crushers, grooves cut in surface to improve grip on feed, and increase angle of nip. Also, in ore concentration in jigs, oversized bedding placed on jig screens. c. See: bedding.

raggy stone
 * Thin-bedded or flaggy sandstone.

ragstone
 * See: rag.

rail
 * The chain or inner surface of a crawler.

rail gage
 * The distance or width between the inner edges of the heads of the rails; (1) in coal mining, the rail gage for tub and car tracks ranges from 2 to 3 ft (0.6 to 0.9 m), and 2-1/3 ft (0.7 m) is considered a satisfactory compromise; (2) the standard gage for railway tracks is 4 ft, 8-1/2 in (1.44 m) and, (3) in metal mining, the rail gage ranges from 1-1/2 to 2-1/2 ft (0.46 to 0.76 m). See also: track gage.

rail haulage system
 * A materials transportation system consisting of gondola cars, and the steel rails on which the cars are moved about with a suitably powered traction unit as a locomotive.

rail riffles
 * These may be either longitudinal or transverse and consist of rails of various sizes, placed in sets usually upside down, either longitudinally in the sluice box, or transversally across the box. They wear well, are rigid, and give some security against theft of gold from the sluice boxes.

rails
 * Specially shaped steel bars which, when laid parallel on crossties and fastened, form a track for vehicles with flanged wheels.

rail track ballast
 * Material placed around and between track ties and tamped under sides and ends of the ties to bring the track to proper grade by filling the space between the bottom of the ties and the graded roadbed.

rainbow chalcedony
 * Eng. A variety of chalcedony of thin concentric layers, which, when cut across, exhibit an iridescence resembling the colors of the rainbow.

rainbow quartz
 * See: iris quartz.

rain chamber
 * A chamber in which fumes, such as those from molten metal, may be condensed by a water shower.

rain gage
 * A device used to measure precipitation (melted snow, sleet, or hail as well as rain). It consists of a receiving funnel, a collecting vessel, and a measuring cylinder. Syn: pluviometer; hyetometer; snow gage.

rainwash
 * a. The washing-away of loose surface material by rainwater after it has reached the ground but before it has been concentrated into definite streams; specif. sheet erosion. Also, the movement downslope (under the action of gravity) of material loosened by rainwater. It occurs esp. in semiarid or scantily vegetated regions.

b. The material that originates by the process of rainwash; material transported and accumulated, or washed away, by rainwater. c. The rainwater involved in the process of rainwash.

raise
 * a. A vertical or inclined opening in a mine driven upward from a level to connect with the level above, or to explore the ground for a limited distance above one level. After two levels are connected, the connection may be a winze or a raise, depending upon which level is taken as the point of reference. Syn: raised shaft See also: upraise; raising; rise.

b. A mine opening, like a shaft, driven upward from the back of a level to a level above, or to the surface. c. To take up the floor or bottom rock in a room, gangway, or entry to increase the height for haulage.

raise borer
 * These machines are used to produce a circular excavation either between two existing levels in an underground mine or between the surface and an existing level in a mine. In raise boring, a pilothole is drilled down to the lower level, the drillbit is removed and replaced by a reamer head having a diameter with the same dimension as the desired excavation and this head then is rotated and pulled back up towards the machine.

raise climber
 * Equipment used in an opening (raise) that is mined upward.

raised shaft
 * See: raise.

raising
 * Excavating a shaft or steep tunnel upward. See also: raise; rise.

rait
 * Mid. To split off the walls or sides of underground workings. Called rosh in Leicestershire. Syn: rate.

rake
 * a. As used by diamond drillers and bit manufacturers, rake is the angle, measured in degrees, formed by the leading face of a cutting tool and the surface behind the cutting edge. See also: negative rake; positive rake.

b. The inclination of anything from the vertical; said of mineral veins, faults, etc. See also: pitch. c. A timber placed at an angle. See also: rakers. d. Shale containing ironstone nodules.

rake blade
 * A dozer blade or attachment made of spaced tines.

rake classifier
 * A type of mechanical classifier utilizing reciprocal rakes on an inclined plane to separate coarse from fine material contained in a water pulp, overflowing the fine material and discharging the coarse material by means of an inclined raking system.

rakers
 * Slanting props placed at the end of a drift set to keep the timbers steady when blasts go off. See also: rake.

rake thickener
 * Equipment for thickening in which the concentrated suspension settles in a container of circular section and is delivered mechanically to one or more discharge points by a series of arms revolving slowly around a central shaft.

rake vein
 * a. A steeply inclined crosscutting irregular mineralized fracture or fissure.

b. Rake vein and gas vein are synonymous; it is said that they are lodes filling distinct fissures. Their course in irregular; their dip, as a rule, vertical. c. A vein or lode cutting through the strata.

raking strut
 * A strut set at an angle to the vertical to support timbering during excavation.

Raky boring method
 * A method of boring somewhat similar to Fauck's. Hollow steel rods 2 in (5.08 cm) in diameter are used with a mud flush. A walking beam, fitted with steel springs, imparts from 80 to 120 short blows/min to the chisel.

Raleigh's law
 * In 1909 Lord Raleigh established the general law of fluid flow: R = wV (super 2) (f)(wVD/m), where R = resistance of flow, w = density of fluid, V = velocity of flow, D = diameter of pipe, m = viscosity of fluid, f = signifies function. For any particular value of (wVD)/m, using any combination of quantities, there will be a definite corresponding value of R/wV (super 2).

ralstonite
 * An isometric mineral, Na (sub x) Mg (sub x) Al (sub 2-x) (F,OH) (sub 6) .H (sub 2) O ; structurally related to the pyrochlore group; occurs as octahedra.

Ralston's classification of coal
 * A classification based on the percentage of carbon, hydrogen, and oxygen in the ash-, moisture-, sulfur-, and nitrogen-free coal. These figures are plotted on trilinear coordinates giving well-defined zones of bituminous coals, lignites, peats, etc.

ram
 * a. To stem; tamp.

b. Black ram, bog iron ore; gold ram, gold ore. c. The plunger of a pump. d. A mechanical pusher for forcing (discharging) coke from a byproduct coke oven. e. An appliance for exerting a pressure on face equipment, such as steel supports, conveyors, or plows. See also: hydraulic ram; pneumatic ram.

ramdohrite
 * A monoclinic mineral, Ag (sub 3) Pb (sub 6) Sb (sub 11) S (sub 24) ; forms dark-gray twinned prismatic to lance-shaped crystals; at Potosi, Bolivia. CF: andorite.

rammel
 * Loose stone, or waste rock; loose sandy or stony barren soil; mixed shale and sandstone. Also spelled: rammell.

rammelsbergite
 * An orthorhombic mineral, NiAs (sub 2) ; loellingite group; trimorphous with pararammelsbergite and krutovite; metallic; tin white; sp gr, 7.1; in vein deposits. Syn: white nickel.

rammer
 * A rod for charging and stemming shotholes. See also: stemmer.

ramming
 * a. See: stemming; tamping.

b. See: scaling.

ramming and patching refractories
 * Those which can be rammed to form a monolithic furnace lining or special shapes.

ram operator
 * In bituminous coal mining, a laborer who tends operation of, adjusts, and repairs pumping devices (rams) used in low places in shallow mines to force a portion of the mine water to the surface by utilization of the flow of the entire amount. Nearly obsolete. See: pumper.

ramp
 * a. A fault that is a gravity (normal) fault near the surface but curves through the vertical to dip in the opposite direction at depth, where the displacement is that characteristic of a thrust.

b. A portion of a thrust fault that cuts across formational contacts in a short distance. c. An incline connecting two levels in an open pit or underground mine.

ram pump
 * a. A pump consisting essentially of a plunger or ram which forces the contained water into the discharge pipe. See also: force pump.

b. A single-acting reciprocating pump that has a ram instead of a piston. The ram has a constant diameter and does not fit closely in the cylinder, pumping only by displacement.

ram scraper
 * a. A valley produced by the ramping or upthrusting of two masses, one on either side of an intervening strip.

b. A valley bounded by thrust faults. N 9�f ��f ��        ��       � 5�DICTIONARY TERMS:ram scraper A plow-type machine hauled by an endles A plow-type machine hauled by an endless chain at a speed of 6 ft/s (1.83 m/s). The ram scraper is pressed toward the face by the tension of the return strand, the return sheave being located inby for this purpose. Syn: Peissenberg ram. See also: manless face.

ramsdellite
 * An orthorhombic mineral, MnO (sub 2) ; trimorphous with akhtenskite and pyrolusite.

rance
 * a. A prop set against the coal face that is undermined.

b. A dull red marble with blue and white markings. From Belgium, and sold in the United States as Belgian marble.

rance marble
 * a. A white, hard, shining grit, striped red.

b. A kind of variegated marble from Hainault, Belgium.

rand
 * S. Afr. A ridge, range of hills, or highland on either side of a river valley.

Rand
 * An abbrev. of Witwatersrand, the gold fields in the Republic of South Africa.

Randolph process
 * A modification of the series process of copper refining in which the electrodes lie horizontally, the top surface of each one acting as anode, the lower as cathode. Theoretically, it has the advantage of extremely low metal losses and great purity of copper. See also: Hayden process; Smith process.

random
 * The direction of a rake vein.

random error
 * Any error that is wholly due to chance and does not recur; an accidental error. Ant: systematic error.

random line
 * a. A trial line, directed as nearly as may be toward a fixed terminal point that is invisible from the initial point.

b. A random traverse; i.e., a traverse run from an initial to a terminal point to determine the direction of the latter from the former.

random orientation
 * See: random set.

random pattern
 * The setting of diamonds in a bit crown without regard to a geometric pattern--without regular and even spacing. See also: random set.

random sample
 * a. A sample take without plan or pattern.

b. A subset of a statistical population in which each item has an equal and independent chance of being chosen; e.g., a sample chosen to determine (within definied limits) the average characteristics of an orebody.

random set
 * The setting of diamonds in a bit crown without regard to the attitude of their vector properties. Syn: random orientation. See also: random pattern.

random stone
 * A term applied by quarry personnel to quarried blocks of any dimensions.

Randupson process
 * A system of molding in which the molds are made of a mixture of silica sand and cement with water added.

rang
 * a. In the CIPW classification of igneous rocks, that division below order.

b. A Ceylonese term for gold; from rangwelle meaning golden sand.

range
 * a. An area in which a mineral-bearing formation crops out; e.g., the iron range and copper range of the Lake Superior region; a mineral belt.

b. An established or well-defined line or course whose position is known and along which soundings are taken in a hydrographic survey. c. Any series of contiguous townships (of the U.S. Public Land Survey system) aligned north and south and numbered consecutively east and west from a principal meridian. d. The distribution of a genus, species, or other taxonomic group of organisms through geologic time. e. An orderly arrangement or family of diamond-drill fittings, such as casing, core barrels, drill rods, etc., with diameters appropriately related to each other and intended to be used together. Ranges commonly are designated by letter names, using letters such as E, A, B, and N individually or as the first letter in two- and three-letter names. CF: group. f. For a spherical model, the distance at which the model reaches its maximum value, or sill. For the exponential and gaussian models, which approach the sill asymptomatically, it means the "practical" or "effective" range, where the function reaches approximately 95% of the maximum. The nugget model effectively has a sill with a range of zero: the linear model uses "sill/range" merely to define the slope.

range line
 * One of the imaginary boundary lines running north and south at six-mile intervals and marking the relative east and west locations of townships in the U.S. public-land survey; a meridional township boundary line. CF: township line.

range of stress
 * The range between the upper and lower limit of a cycle of stress, such as is applied in a fatigue test. The midpoint of the range is the mean stress.

range pole
 * a. A 6- to 12-ft (2- to 3-m) wooden or metal pole painted in contrasting colors at 1-ft (0.3-m) intervals. It is used in surveying to mark lines of sight, stations, etc.

b. See: picket. c. A metal rod, pointed at one end, and usually painted alternately red and white at 1-ft intervals; used by surveyors as a line of sight. Syn: ranging rod.

ranging rod
 * See: range pole.

rank
 * a. Describes the stage of carbonification attained by a given coal.

b. The place occupied by a coal in a classification. Specifications of the American Society for Testing and Materials cover the classification of coals according to their degree of metamorphism, or progressive alteration, from lignite to anthracite. For a complete description of this classification, consult ASTM Designation: D 388. c. When applied to coal, denotes its age in geological formation, not necessarily denoting quality. d. The position of a coal relative to other coals in the coalification series from brown coal (low rank) to anthracite (high rank), indicating its maturity in terms of its general chemical and physical properties. e. Those differences in the pure coal material due to geological processes designated as metamorphic, whereby the coal material changes from peat through lignite and bituminous coal to anthracite or even to graphite. f. All coallike fossil fuels form a continuous and progressive series, ranging from lignite, through the various bituminous coals, to anthracite. It is the position of a particular coal in this series that determines its rank. Therefore, lignite is a low-rank coal while anthracite is a high-rank coal. See also: coalification; grade; Hilt's Law; coal rank. g. A term primarily devised to indicate the position of a fuel in the series peat-anthracite, probably best measured by the percentage of carbon (ashless, dry basis). Thus rank depends on the degree of metamorphism of coal, and increase of rank is, in general, marked by the decrease of volatiles and moisture. h. The term rank may also be applied to other series, such as the sapropelic coal series or the bitumen series. CF: type.

Rankine scale
 * An absolute-temperature scale in which a measurement interval equals a Fahrenheit degree and in which zero degrees is equal to -459.67 degrees F (-273.16 degrees C). Named for William J.M. Rankine, a Scottish physicist. See also: temperature.

Rankine's formula
 * An empirical formula giving the collapsing load for a given column.

Rankine's theory
 * The state of stress theory as developed by Rankine in 1860 for application to earth pressures. He formulated that the pressure on a vertical retaining wall restraining earth with a horizontal surface is (1 - sinphi ) / (1 + sinphi ) multiplied by the soil density for each foot depth of soil retained, where phi is the angle of internal friction of the soil. The value (1 - sinphi ) / (1 + sin#2f) is the coefficient of active earth pressure.

rankinite
 * A monoclinic mineral, Ca (sub 3) Si (sub 2) O (sub 7) ; dimorphous with kilchoanite; rare in contact metamorphic rock, but common in blast furnace slag.

rank variety
 * Variety in coals brought about as a result of progressive metamorphism. More or less arbitrarily, although carefully, selected chemical criteria are used to differentiate coals of different rank. Physical criteria are also used but are more difficult of application.

ransomite
 * A monoclinic mineral, CuFe (sub 2) (SO (sub 4) ) (sub 4) .6H (sub 2) O ; forms slender sky-blue prisms; at Jerome, AZ.

rap
 * a. To warn workers in an adjoining working place of a blast, when the working places are separated by only a small pillar, by knocking on the pillar with a tool or bar.

b. To test the roof by tapping it with a stick or bar. c. To signal by knocking on a steam, water, or air pipe.

rapakivi
 * A hornblende-biotite granite containing large rounded crystals of orthoclase mantled with oligoclase. The name has come to be used most frequently as a textural term where it implies plagioclase rims around orthoclase in plutonic rocks.

rapid blow drilling
 * A drilling method utilizeing a great number of short blows in quick succession rather than a few heavy blows from a relatively considerable altitude. In this method, the bit is fixed either to a rod or to a rope, so that it pounds the bottom in quick succession with short blows and at the same time rotates.

rapid excavation
 * An improved cycle and system of operation to achieve rapid advance and continuous operation in low-drillability rock.

rapid plow
 * A fast moving plow with picks attached. The rapid plow is a continuous longwall cutter loader capable of working unattended on the face. For this reason, it is one of the safest machines in operation. See also: hard-coal plow.

rap-in
 * Som. To wedge down blocks of stone in underground quarries.

rappage
 * Excess in size of a casting because the mold is larger than the pattern when the latter is unduly rapped, as with the hand, for drawing.

rapping
 * In foundry work, loosening of pattern before its withdrawal from molding sand in flask.

rapping roller
 * An eccentric roller or a roller fitted with devices such as bars welded longitudinally along its outer casing, so arranged as to rap the belt and knock off fine coal or dust adhering to the return belt, or to centralize the coal on the carrying belt.

rare earths
 * Oxides of a series of 15 metallic elements, from lanthanum (atomic number 57) to lutetium (71), and of two other elements; yttrium (39), and scandium (21). These elements are not esp. rare in the Earth's crust, but concentrations are. The rare earth metals resemble one another very closely in chemical and physical properties, thus making it most difficult to separate them. The rare earths are constituents of certain minerals, esp. monazite, bastnaesite, and xenotime. Abbrev: REE.

rarefaction
 * a. The process or act of making rare or less dense; increase of volume, the mass remaining the same: now usually of gases; also, the state of being rarified; as, the rarefaction of the atmosphere on a high mountain.

b. Diminution of air pressure below normal, as in alternate half-cycles in the transmission of a sound wave past a point.

rashings
 * A very friable carbonaceous clay, with numerous slickensides and sometimes streaks of coal. Rashings may underlie, overlie, or be interstratified with the coal; a very weak material and breaks up around the face supports. See also: brashings.

Rasorite
 * See: kernite. A trade name for kernite.

rasp
 * An instrument used in a borehole for fishing operations, for reducing the length of the box, or for coupling lost tools. Also called mill; rose bit.

raspberry spar
 * a. See: rhodochrosite.

b. Pink tourmaline.

raspite
 * A monoclinic mineral, PbWO (sub 4) ; dimorphous with stolzite; forms small tabular brownish-yellow crystals having intense adamantine luster; at Broken Hill, N.S.W., Australia.

ratchet
 * A set of teeth that are vertical on one side and sloped on the other; holds a pawl moving in one direction, but allows it to move in another.

ratchet-and-pawl mechanism
 * A cogwheel (ratchet) with which a single pivoted catch (pawl) engages, thereby preventing any backward turning.

ratchet drill
 * A hand drill in which the drill holder is revolved intermittently by a lever through a ratchet wheel and pawl. A drill used for boring slate.

ratchet man
 * The worker who operates the duckbill loader when mining with duckbill conveyors.

rate
 * See: rait.

rate action (nonstandard)
 * As used in flotation, the component of proportional plus rate action or of proportional plus reset plus rate action for which there is a continuous linear relation between the rate of change of the controlled variable and the position of a final control element.

rated capacity
 * The load that a new wire rope or wire rope sling may handle under given operating conditions and at an assumed design factor.

rate determining step
 * In any series or sequence of chemical reactions used to leach a product from its ore, the slowest in the chain.

rated horsepower
 * a. Theoretical horsepower of an engine based on dimensions and speed.

b. Power of an engine according to a particular standard.

rated load
 * The kilowatt power output that can be delivered continuously at the rated output voltage. It may also be designated as the 100% load or full-load rating of the unit.

rated output current
 * The current derived from the rated load and the rated output voltage.

rated output voltage
 * The current specified as the basis of rating.

rate of advance
 * a. The distance the bit penetrates a rock formation in a unit of time, such as inches (centimeters) per minute or feet (meters) per hour.

b. In coal mining, the number of feet (meters) between the coal face at the beginning and at the end of a workshift.

rate of grade
 * See: gradient.

rates of reduction
 * In crushing practice, these rates are (1) based on crusher dimensions, wherein the largest cube that will enter is compared with the largest that can be discharged, or (receiving opening) / (discharge opening); the receiving opening is measured from the top of the movable member to the top of the stationary member; and (2) based on actual products; (a) overall reduction ratio = (mean size of feed) / (mean size of product); (b) individual reduction ratio = (size most abundant in feed) / (mean size of grading band concerned).

rathite
 * See: liveingite.

rathite-II
 * See: liveingite.

rathole
 * a. A hole drilled at an angle to the main hole by means of a deflection wedge.

b. A small-diameter pilot-type hole drilled a short distance ahead of a larger diameter hole to stabilize a smaller diameter bit and core barrel when used to core a limited portion of the borehole. After core drilling is completed, the rathole is reamed out and the larger size hole advanced, usually by some noncoring method. c. A small sump or settling pond in which the larger sized cuttings from a drill hole are collected between the top of the drill hole and the main settling pond. d. A slanting hole, perhaps 25 ft (7.62 m) deep, used for adjusting or lubricating the swivel on a grief stem. The start of a hole for rotary drilling.

rathole bit
 * A bit designed and used to drill the first portion of a deflected hole alongside and beyond the deflection wedge; also, a bit used to drill a rathole. CF: wedge bit. See also: rathole.

rat-holing
 * The act or process of drilling a deflected or pilot hole. See also: rathole.

rating
 * The maximum capacity of a drill hoist or a prime mover, such as an engine, motor, or pump; generally the maximum safe capacity.

rating flume
 * A flume used for purposes of control.

ratiometer
 * An instrument used to measure the ratio of two differences in potential.

rational analysis
 * a. The mineralogical composition of a material as deduced from chemical analysis.

b. The resolution into chemical types of a mass of rock or coal.

ratio of absorption
 * a. The percentage by weight that the absorbed water bears to the dry weight of the stone.

b. The ratio (A), expressed as a percentage, of the volume (Vp) of the pore space in a rock to the weight (W) of the rock when dry, A = 100 Vp/W.

ratio of concentration
 * (Weight of ore fed) / (Weight of concentrate produced).

ratio of enrichment
 * The ratio of the percentage of valuable material in the concentrate to the percentage of the valuable material in the original material.

ratio of reduction
 * a. The relationship between the maximum size of the stone which will enter a crusher, and the size of its product.

b. The ratio of enrichment with respect to the sought mineral: (Assay value in feed) : (Assay value in concentrate). See also: reduction ratio.

ratio of size reduction
 * Ratio of the upper particle size in the crushed material to the upper particle size of the feed material.

rattle boxes
 * Limonite geodes from Chester County, PA.

rattler
 * a. York. Cannel coal.

b. Scot. Inferior gas coal; sandy shale. c. U.K. A variety of gas coal that fetched high prices and was reputed to ignite with a match. It is hard, compact, uniform, bright, brittle, fine-grained, slightly sonorous when struck, and resembling jet but not so brilliant. d. A revolving steel drum with a charge of metal spheres used for testing the abrasive resistance of brick. e. A device for shaking out the cores from small castings, such as a tumbling barrel.

rattler test
 * A method for evaluating the resistance of paving bricks to impact and abrasion. A sample of 10 bricks is subjected to the action of 10 cast-iron balls 3.75 in (9.53 cm) in diameter and 245 to 260 balls 1.875 in (4.76 cm) in diameter in a drum 28 in (71.12 cm) in diameter, 20 in (50.8 cm) long, rotating at 30 rpm for 1 h. The severity of abrasion and impact is reported as a percentage loss in weight.

rattlesnake ore
 * A gray, black, and yellow mottled ore of carnotite and vanoxite, its spotted appearance resembling that of a rattlesnake.

rauvite
 * A mineral, Ca(UO (sub 2) ) (sub 2) V (sub 10) O (sub 28) .16H (sub 2) O ; radioactive; purple- black; sandstone impregnation on the Colorado Plateau.

ravelly ground
 * Rock that breaks into small pieces when drilled and tends to cave or slough into the hole when the drill string is pulled, or binds the drill string by becoming wedged or locked between the drill rod and the borehole wall.

ravine
 * A small, narrow, deep depression, smaller than a gorge or a canyon but larger than a gully, usually carved by running water; esp. the narrow excavated channel of a mountain stream. Etymol: French, mountain torrent.

raw
 * a. In ceramics, fresh from a plastic process; unbaked.

b. Not prepared for use by heat.

raw coal
 * Coal which has received no preparation other than possibly screening. Syn: raw ore.

raw coal screen
 * A screen used for dividing run-of-mine coal into two or more sizes for further treatment or disposal; usually employed to remove the largest pieces for crushing and readdition to the run-of-mine coal.

raw dolomite
 * a. Dolomite that has not been calcined.

b. Crushed dolomite used for dressing of basic open hearth bottoms and banks.

raw feed coal
 * Coal supplied to a plant or machine, in which it undergoes some form of preparation.

raw fuel
 * A fuel used in the form in which it is mined or obtained, for example, coal, lignite, peat, wood, mineral oil, natural gas.

rawhide hammer
 * A hand hammer having a rawhide head that serves to prevent bruising metal parts against which it is used.

raw material
 * The ingredients before being processed that enter into a finished product.

raw mica
 * A term commonly used for unmanufactured mica.

raw ore
 * a. Ore that is not roasted or calcined.

b. See: raw coal.

raydist
 * A radio system for medium-range precision surveying in which the phases of two continuous-wave signals are compared. It is based on the heterodyne principle and uses low or medium frequencies. It requires a minimum number of frequencies and these frequencies usually need bear no fixed relationship with each other.

Rayleigh wave
 * a. A type of seismic surface wave having a retrograde, elliptical motion at the free surface. It is named after Lord Rayleigh, the English physicist who predicted its existence. Syn: R wave.

b. A surface wave associated with the free boundary of a solid. The wave is of maximum intensity at the surface and diminishes quite rapidly as one proceeds into the solid. Therefore, it has a tendency to hug the surface of the solid. Such waves have been used quite effectively in detecting surface cracks and flaws in castings.

Raymond flash dryer
 * A suspension-type dryer that employs the principle of flash drying of fine coal. The coal is transported vertically through a drying column in a stream of hot gases. The source of heat for this system is usually an automatic stoker. In this system, the hot gases are drawn into the drying column by the action of the fan connected to the cyclone collector vent. The coal to be dried is continuously introduced to the hot gas stream. Virtually instantaneous drying occurs. The dried coal and the moisture-laden gases are drawn into the cyclone collector. The dry coal drops to the bottom of the collector and the moisture-laden gases are discharged by the fan to the atmosphere. See also: thermal drying.

Raymond mill
 * Grinding mill in which spring-loaded rollers bear against a horizontal rotating bowl--developed for coal pulverization.

rays
 * a. Negatively charged particles which leave the cathode in an evacuated tube at between 10,000 mi/s and 90,000 mi/s (approx. 16,000 km/s and 144,000 km/s), depending on voltage. Positive rays are gas ions (e.g., N (super +), O (super +) ). X-rays are electromagnetic waves which travel at the velocity of light and are not deflected by magnetic fields. Length between 0.1 and 100 Aa (visible light lies between 4,000 and 8,000 Aa). Short X-rays are soft and long ones are hard. Rays emitted by radioactive substances are of three types, alpha, beta, and gamma. Alpha rays consist of He (super ++) and move at some 10,000 mile/s (approx 16,000 km/s). Beta rays are electrons with speeds between 50,000 mi/s and 180,000 mi/s (approx. 80,000 km/s and 288,000 km/s); gamma rays are not charged. They move at the speed of light, but are shorter than X-rays (0.01 to 1 Aa).

b. In wave propagation a ray is the trajectory that a signal travels from the source to another point (location).

raywork
 * A kind of rubble work; in the United States, any rubble work of thin and small stones.

razorback
 * A sharp, narrow ridge, resembling the back of a razorback hog.

razor saw
 * A narrow saw used in excavating limestone.

razor stone
 * See: novaculite.