Appendix:Dictionary of Mining, Mineral, and Related Terms/R/4

rib
 * a. The side of a pillar or the wall of an entry.

b. The solid coal on the side of a gallery or longwall face; a pillar or barrier of coal left for support. c. The solid ore of a vein; an elongated pillar left to support the hanging wall in working out a vein. d. A stringer of ore in a lode. e. The termination of a coal face. Where solid coal is left, the term fast rib, end, or side, is used; and where the coal face ends at the gob, the term used is loose rib, end, or side. f. See: buttock. g. A hard zone, bed, or horizon within a formation; a silicified zone in a sedimentary stratum. h. A ridge projecting above grade in the floor of a blasted area. i. A ridge, paralleling the long axis of a drill string member, that acts as a wear-resistant surface.

ribbed roll
 * A crusher in which the material passes between a moving set of rolls with ribs on their surfaces parallel to the axis of the rolls. See also: roll.

ribbing
 * Enlarging a heading or drift.

ribbon
 * a. One of a set of parallel bands or streaks in a mineral or rock, e.g., ribbon jasper; when the lines of contrast are on a larger scale, the term banding is used. See also: stripe.

b. Said of a vein having alternating streaks of ore with gangue or country rock, or simply of varicolored ore minerals. CF: banded; book structure. c. A color band in slate that represents original bedding and crosses the superimposed slaty cleavage. Ribbon is generally undesirable and decreases the value of the slate. Syn: pancake.

ribbon brake
 * A friction brake having a metal strap that encircles a wheel or drum and may be drawn tightly against it. A band brake.

ribbon diagram
 * Geologic cross section drawn in perspective and joining control points along a sinuous line.

rib boss
 * See: pillar boss.

rib dust
 * Dust found on the side walls of a mine. The dust from the roof is generally included with this sample.

rib hole
 * Final holes fired in blasting around sides of shaft or tunnel. Also called trimmer.

rib line
 * A continuous line along which pillars are mined. See also: break line.

rib lining
 * In rod or ball mill, replaceable ribs that project longitudinally from shell liners so as to act as lifters for crop load as mill rotates.

rib mesh
 * Expanded metal stiffened at intervals with bent steel plates.

rib pillar
 * A pillar whose length is large compared with its width.

ribs
 * The lines or ridges of cut gems that distinguish the several parts of the work, both of brilliants and roses.

rib-side
 * The side of a heading or roadway driven in the solid coal. See also: narrow stall.

rib-side gate
 * A gate road in longwall mining with a rib of solid coal along one side.

rib-side pack
 * A pack formed by working 5 to 10 yd (4.6 to 9.1 m) of coal along a rib-side of a road and packing the waste. See also: roadside pack; skipping.

rice coal
 * a. Anthracite coal of a small size; No. 2 Buckwheat coal. See also: anthracite coal sizes.

b. A steam size of anthracite.

Richards' pulsator classifier
 * A classifier operating in such a manner that the pulp grains fall through a sorting column against an upward pulsating current of water. It has no screen.

Richards' pulsator jig
 * An outcome of the pulsator classifier, in which a pulsating column of water is used in the jig. See also: pulsator jig.

Richards' shallow-pocket hindered-settling classifier
 * A series of pockets through which successively weaker streams of water are directed upward. The material that can settle does so, and is drawn off through spigots.

richetite
 * A triclinic mineral, PbU (sub 4) O (sub 13) .4H (sub 2) O ; strongly radioactive; black; occurs embedded among fine needles of uranophane.

richmondite
 * a. A discredited mineral term since a number of specimens have proved to be mixtures containing, in order of abundance, argentian tetrahedrite, galena, sphalerite, chalcopyrite, pyrite, and perhaps stromeyerite.

b. A mixture of sulfide minerals containing silver, lead, zinc, and copper.

rickardite
 * An orthorhombic mineral, Cu (sub 7) Te (sub 5) ; pseudotetragonal; deep purple; at Vulcan and Bonanza, CO; Warren, AZ; and Salvador, Brazil.

ricket
 * An airway along the side of an adit or shaft. Also called ricketing.

rid
 * See: redd.

ridding
 * N. of Eng. Separating ironstone from coal shale. See also: redd.

riddle
 * a. A barrel-shaped, revolving perforated drum in which blank coins are washed and dried after passing through a bath of sulfuric acid.

b. A coarse sieve. The large pieces of ore and rock picked out by hand are called knockings. The riddlings remain on the riddle; the fell goes through. c. A sieve used to separate foundry sand or other granular materials into various particle-size grades or free such a material of undesirable foreign matter.

ride over
 * Arkansas. A squeeze that extends into the workings beyond the pillar. It is said to ride over a pillar.

rider
 * a. A thin coal seam above a workable seam, or a seam that has no name.

b. The rock lying between two lodes or beds; a mass of country rock enclosed in a lode; a horse. c. An ore deposit overlying the principal vein. d. A steel or iron crossbeam which slides between the guides in sinking a shaft. It is carried up and down by, but is not attached to, the hoppit, which it guides and steadies.

ridge
 * a. A long, narrow elevation of the Earth's surface, generally sharp crested with steep sides, either independently or as part of a larger mountain or hill.

b. A long elevation of the deep-sea floor having steeper sides and less regular topography than a rise.

ridge fillet
 * A runner or principal channel for molten metal.

ridge terrace
 * A ridge built along a contour line of a slope to pond rainwater above it.

Ridgeway fiter
 * A horizontal, revolving, continuous vacuum filter. The surface is an annular ring consisting of separate trays with vacuum and compressed air attachments. The filtering surface is on the underside, the trays being dipped into the tank of pulp to form the cake and then lifted out of it.

riding
 * Said of mine timbering when the sets are thrust out of line, or lean.

Ridley-Scholes bath
 * Dense-media system used to float coal away from shale, the latter falling to the bottom of a wedge-shaped pool of separating fluid and being withdrawn by a rising belt.

rid-up runners
 * To clean up after a cast, as when the scrap, slag, and iron is removed from runners, troughs, and skimmers, and they are freshly clayed, loamed, or sanded.

riebeckite
 * A monoclinic mineral, Na (sub 2) Ca(MgFe (super +2) ) (sub 5) Si (sub 8) O (sub 22) (OH) (sub 2) ; amphibole group with Mg/(Mg+Fe (super 2+) ) = 0 to 0.49 and Fe (super 3+) /(Fe (super 3+) +Al) = 0.7 to 1.0; forms a series with magnesioriebeckite; fibrous; in soda-rich rhyolites, granites, and pegmatites; crocidolite variety is blue asbestos, tiger eye is crocidolite replaced by quartz. CF: glaucophane.

Riecke's principle
 * The statement in thermodynamics that solution of a mineral tends to occur most readily at points where external pressure is greatest, and that crystallization occurs most readily at points where external pressure is least. It is applied to recrystallization in metamorphic rocks with attendant change in mineral shapes, such that mass is transferred from contact points to pressure shadows resulting in reduced rock porosity. It is named after the German physicist E. Riecke (1845-1915) although it was actually discovered and described by Sorby in 1863.

riemannite
 * See: allophane.

riffle
 * a. A natural shallows extending across a stream bed over which the water flows swiftly and the water surface is broken into waves; a shallow rapids of comparatively little fall.

b. The lining of the bottom of a sluice, made of blocks or slats of wood or stones, arranged in such a manner that chinks or slots are left between them, into which heavy mineral grains fall and are held for recovery. c. The raised portions of the deck of a concentrating table, that serve to trap the heaviest particles. Syn: ripple. d. A device used to reduce the volume or weight of a sample consisting of a thin metal plate on which is mounted a series of metal strips to guide or deflect a small portion of the sample material into a separate container. CF: sample splitter. See also: ripple board. e. Sample reducing device such as Clark riffler or Jones riffle, which splits a batch sample of ground ore into two equal streams as it falls across an assembly of deflecting chutes. See also: sludge sampler. CF: Jones splitter.

riffle bars
 * Slats of wood nailed across the bottom of a cradle or other gold-washing machine for the purpose of detaining the gold.

riffle box
 * A device designed to reduce a sample of coal or ore to half its original size. The box contains about 12 chutes discharging alternately to opposite sides. The width varies according to the largest particle size. The volume reduction is rapid for dry material of suitable fineness.

riffler
 * See: sample splitter.

rifle
 * a. As used by drillers, a borehole that is following or has followed a spiral or corkscrew course; also said of a drill core that has spiral grooves appearing on its outside surface.

b. A drill hole, in rock, that has become three-cornered while drilling. c. Applied to the three-cornered section of a hole drilled by hand. Though the bit is supposed to be turned one-eighth after each blow, to insure a circular hole, the majority of hand-drilled holes are three-cornered.

rifle bar
 * A cylinder with curved splines.

rifle nut
 * A splined nut that slides back and forth on a rifle bar.

rifling
 * a. Working coal which was left behind over the waste.

b. The spiral grooving in the walls of a drill hole and/or on the surface of a drill core. c. A borehole following a spiraled course.

rift
 * a. A regional-scale strike-slip fault, e.g., the San Andreas rift in California, with offset measured in hundreds of kilometers.

b. A trough or valley formed by faulting. c. In quarrying, a direction of parting in a massive rock, such as granite, at approx. right angles to the grain. CF: grain; hard way. d. A narrow cleft, fissure, or other opening in rock (such as in limestone), made by cracking or splitting. e. A planar property whereby granitic rocks split relatively easily in a direction other than the sheeting (parallel to the surface of the Earth.) f. A term used in slate quarrying to describe a second direction of splitting less pronounced than slaty cleavage and usually at right angles to it. g. In sedimentary rocks, the horizontal plane of stratification, or the bed of the rock. h. An obscure foliation, either vertical (or nearly so) or horizontal, along which a rock splits more readily than in any other direction. Syn: fault trace. i. A crack, such as in the mid-ocean ridges.

rifter-trimmer
 * One who separates blocks of mica into sheets and trims sheets preparatory to processing. Also called full trimmer.

rifting
 * The process of splitting hand-cobbed mica into sheets of usable thicknesses.

rift structure
 * A long, narrow structural trough that is bounded by normal faults; a graben of regional extent. CF: rift valley.

rift valley
 * a. A valley that has developed along a rift structure. Syn: fault trough.

b. The deep central cleft in the crest of the mid-oceanic ridge. Syn: midocean rift. See also: Mid-Atlantic Ridge.

rift zone
 * a. A system of parallel crustal fractures; a rift structure.

b. In Hawaii, a zone of volcanic features associated with underlying dike complexes. Syn: volcanic rift zone.

rig
 * a. A drill machine complete with auxiliary and accessory equipment needed to drill boreholes.

b. To assemble and set up a tripod, derrick, and/or drill machine and put it in order for use. Syn: rig up. See also: setup. c. A general term denoting any machine. More specif., the front or attachment of a revolving shovel. See also: drilling rig.

rigged
 * Drill machine and equipment in place at a drill site and ready to start drilling.

rigger
 * One who, with special equipment and tackle, moves and transports heavy machinery, etc.

rigging
 * a. Process of setting up a drill and its auxiliary equipment preparatory to drilling. Syn: setting up.

b. The cables or ropes anchoring a drill derrick, mast, or tripod. See also: guy. c. Sometimes used as a term for derrick, mast, or tripod complete with anchor, stay ropes, and cables. d. The equipment or gear such as hoists, tackle, winches, chains, or rope used by riggers in their work. e. The engineering design, layout, and fabrication of pattern equipment for producing castings; including a study of the casting solidification program, feeding and gating, risering, skimmers, and fitting flasks.

rigging bar
 * A long, extension-type jack bar or drill column for use underground, on which a drilling machine can be mounted.

right-angled block
 * In quarrying, a block of stone bounded by three pairs of parallel faces, all adjacent faces meeting at right angles.

right bank
 * The bank of a stream that is on the right when one looks downstream.

right-hand cutting tool
 * A cutter, all of whose flutes twist away in a clockwise direction when viewed from either end.

right-hand feed screw
 * A diamond-drill feed screw that rotates in a clockwise direction.

right-hand lay
 * Rope or strand construction in which wires or strand are laid in a helix having a right-hand pitch. See also: lay.

right lang lay
 * Wire or fiber rope or cable in which the individual wires or fibers forming a strand and the strands themselves are both twisted to the right. Also called right long lay.

right-lateral fault
 * A fault on which the displacement is such that the side opposite the observer appears displaced to the right. CF: left-lateral fault. Syn: dextral fault.

right lay
 * Wire or fiber rope or cable in which the strands formed from a group of individual wires or fibers are twisted to the right.

right line
 * A straight line; the shortest distance between two points.

right long lay
 * See: right lang lay.

right-of-way
 * A grant by Act of Congress, to convey water over or across the public domain, for mining purposes.

right regular lay
 * Wire or fiber rope or cable in which the wires or fibers in the strand are twisted to the left and the strands to the right. Syn: regular-lay right lay.

right running
 * a. N. of Eng. Applied to a vein carrying ore in beds often unproductive.

b. N. of Eng. Rake veins extending approx. east and west.

rigid arch
 * A continuous arch which is fully fixed throughout.

rigid coupling
 * A rod-to-feed-screw sub or rod-to-drive-rod sub by means of which the drill rods are coupled directly to the feed screw or drive rod of the diamond-drill swivel head, and the chuck is discarded or eliminated. Also called screw-to-rod adapter.

rigid double tube
 * See: rigid-type double-tube core barrel.

rigid ducts
 * See: ventilation ducts.

rigid foam
 * Formed by mixing isocyanate and a polyether polyol containing a halogenated hydrocarbon agent. Mixing releases heat, causing the foam to expand as much as 30 times the original volume of the liquid. The foam, which becomes cellular and rigid within minutes, is heat resistant and essentially impervious to air and water, and has substantial binding strength. Its characteristics suggest possible uses in mining for insulation, stoppings to control ventilation, and seals to control water and to consolidate broken ground.

rigid frame
 * A framed structure having columns and beams rigidly connected; there are no hinged joints in this type of structure.

rigid hammer crusher
 * A machine in which size reduction is effected by elements rigidly fixed to a rotating horizontal shaft mounted in a surrounding casing.

rigidity
 * The property of a material to resist applied stress that would tend to distort it. A fluid has zero rigidity.

rigidity modulus
 * See: modulus of rigidity. CF: modulus of elasticity.

rigid pavement
 * A road, taxitrack, or hardstanding constructed of concrete slabs.

rigid solution
 * Solubility of solution of elements in a natural glass as compared with a solid solution that implies crystallinity.

rigid-type double-tube core barrel
 * A double-tube core barrel in which both the outer and inner tubes are rigidly connected to a single headpiece. Syn: rigid double tube.

rigid urethane foam
 * See: rigid foam.

rig-up
 * See: setting up.

rig up
 * See: rig.

rig-up time
 * The time required to set up and make a drill rig ready for use at the site where a borehole is to be drilled. Also called setup time; rigging time; mobilizing a rig.

rill
 * To mine ore in such as way that it runs down a slope to a chute or loading level. Ore is said to be rilled to a chute when it is rolled down a slope left in mining.

rill stope
 * Overhand stope so shaped that miners can stand on the ore they have severed, and work horizontally along the side walls of unbroken ore that confine the excavation. The stope is carried as an inverted stepped pyramid, its apex ending in a winze that leads to the tramming level, down to which ore gravitates or is moved.

rim
 * a. The border, edge, or face of a cliff, as at the Grand Canyon of Arizona.

b. The outermost portion of a zoned crystal, e.g., a reaction rim.

rim flying
 * A reconnaissance method in which a plane follows an outcrop along steep canyon walls, keeping where possible within 50 ft (15 m) of the face of the cliff. This type of prospecting has been successful in discovering new deposits in the Colorado Plateau region.

rimmed steel
 * A low-carbon steel containing sufficient iron oxide to give a continuous evolution of carbon monoxide while the ingot is solidifying, resulting in a case or rim of metal virtually free of voids. Sheet and strip products made from the ingot have very good surface quality.

rimrock
 * a. The outcrop of a horizontal layer of resistant rock, such as sandstone, at the edge of a plateau, butte, or mesa; the cliff or ledge so formed.

b. The bedrock rising to form the boundary of a placer deposit.

rimrocking
 * Prospecting for carnotite on the Colorado Plateau, where the favorable beds, more or less flat-lying, crop out in cliffs or rims.

rim texture
 * A texture in ores where the metasome forms a narrow rim around grains of the host mineral.

rim walking
 * Prospecting a canyon rim with a Geiger counter.

rincon
 * a. A term used in the Southwestern United States for a recess or hollow in a cliff or a reentrant in the borders of a mesa or plateau. Also called a cove.

b. A term used in the Southwestern United States for a small, secluded valley. c. A bend in a stream.--Etymol: Spanish rincon, inside corner, nook.

ring
 * a. A complete circle of tubbing plates around a circular shaft. Syn: tunnel lining.

b. Troughs placed in shafts to catch the falling water, and so arranged as to convey it to a certain point. c. See also: wedging crib. d. S. Staff. A circular piece of wrought iron, about 8 in (20 cm) deep, placed on the top of a skip of coal to increase its capacity.

ring arch
 * One composed of a series of straight, unbonded rows, one brick wide.

ring coal
 * a. An old name for bituminous coal.

b. Bituminous coal as opposed to stone coal or anthracite.

ring complex
 * An association of ring dikes and cone sheets.

ring crusher
 * a. A type of hammermill with a high-speed horizontal shaft upon which a series of steel rings are swung.

b. Impact mill, beater mill, or hammermill, in which the beaters are loosely swinging rings. c. See also: hammermill.

ring-cut
 * Holes in a ring around one central hole used to carry a cavity forward, usually six.

ring dike
 * A subcircular to circular dike with steep dip. Ring dikes may be many kilometers long, and hundreds or thousands of meters thick. Their radius is generally from 1 to 20 km. Although some ring dikes may form a nearly complete circle, more commonly they encompass 1/4 to 3/4 of a circle or ellipse. They are commonly associated with alkalic igneous complexes and carbonatites, so are probably related to deep shock effects or to cauldron subsidence. Ring dikes are commonly associated with cone sheets to form a ring complex. Syn: ring-fracture intrusion.

ringed out
 * A diamond bit in the face of which has been gouged a circular groove deeper than, and at least as wide as, the diameter of one row of the inset diamonds.

ringer
 * A crowbar.

ring fault
 * A steep ring-shaped fault, complete or incomplete. It is associated with cauldron subsidence.

ring-fracture intrusion
 * See: ring dike.

ring holes
 * The group of boreholes radially drilled from a common-center setup. See also: horadiam; radial drilling.

ring-induction method
 * An inductive method in which the primary coil and the measuring coil are concentric.

ringing
 * The audible or ultrasonic tone produced in a mechanical part by shock, and having the natural frequency or frequencies of the part. The quality, amplitude, or decay rate of the tone may sometimes be used to indicate quality or soundness.

ring main
 * Closed loop of piping, including provision for entry of material, circulation boost and controlled withdrawal points; used for circulating solids such as pulverized fuel, or fluids such as lime slurry, continuously without settlement or chokeup.

ring ore
 * Fragments of gangue covered with deposits of other minerals. See also: cockade ore.

ring pit
 * A circular pit in which a large wheel is revolved for tempering clay.

ring-roll crusher
 * A type of crusher in which high-speed rolls act on the inside circumference of a vertical cylinder to powder raw material like clay.

ring-roll grizzly
 * A sturdily built grizzly for handling large pieces of ore. This type transports its material across a series of grooved rollers moved mechanically, or alternatively by the sliding ore. Undersize falls through the grooves.

ring-roll press
 * A press consisting of rolls of unequal diameter, revolving one within the other and in the same direction.

Ringrose methane recorder
 * A recorder that gives a continuous record in the range of 0% to 3%.

Ringrose pocket methanometer
 * A small instrument that is capable of estimating methane in the range of 0% to 2%.

ring-shaped occurrences
 * In some areas altered rock has been found as a halo over an orebody and thus serves as a geologic target for guiding prospecting operations. The ratio between the size of the ring and the orebody must not be too large for practical purposes. Such target rings are not always obvious and will only be recognized after much painstaking work and study. Also called bulls-eye alteration patterns.

ring stone
 * a. A voussoir showing on the face of the wall.

b. Eng. Large oolitic grains in very hard crystalline matrix, above the slates at Collyweston, U.K. CF: sun bed.

ring stress
 * The zone of stress, higher than that pre-existing in the rock, which surrounds all development excavations is called the ring stress.

ring-stress bursts
 * In stoping, the ring stresses around a level, rise, or winze are so increased by the influence of an approaching stope face that at some point on the periphery the rock fails. The stress ring is broken, and the rock of sides, back, and bottom released thereby expands suddenly and violently into the excavation, causing a rock burst. This rock burst is identical in type with those occurring in development. It is usually extremely local in effect, though a heavy earth tremor is caused.

ring tension
 * Tension that develops in the wall of a circular tank containing liquid or solid material.

ring-type reaming shell
 * In drilling, a reaming shell, the inset reaming diamonds of which are set into a cast- or powder-metal band encircling the outside surface of the shell.

ring-type wedge
 * A drill-hole deflecting wedge having a short metal sleeve attached to the uppermost end. The outside diameter of the sleeve is the same as that of the lower, full-circle part of the wedge.

ring wall
 * The inner firebrick wall of a blast furnace.

rinkite
 * A monoclinic mineral, (Na,Ca,Ce) (sub 3) Ti(Si (sub 2) O (sub 7) ) (sub 2) OF (sub 3) ; weakly radioactive; forms prismatic crystals in veins containing silicates of cerium metals, yttrium, and niobium; near Barkevik, Norway, in sodalite syenite in the Julianehaab district, Greenland, and in large crystals on the Kola Peninsula, Russia. Also spelled rinkolite. Syn: johnstrupite.

Rinman scale
 * A Swedish standard scale for the estimation of slag inclusions in iron and steel. This scale consists of a series of micrographs, designed to show different typical fields of view, and arranged in groups according to the form and distribution of the inclusions and numbered according to their quantity.

rinneite
 * A trigonal mineral, K (sub 3) NaFeCl (sub 6) ; colorless to varicolored; becomes brown on exposure to air and has an astringent taste.

rinsing
 * In the ion-exchange (IX) cycle, applied to pregnant leach liquors, the displacement wash used after the absorption cycle, which moves pregnant liquor still in the column onto the next absorption column in the series. Term also applied to water rinse used after elution cycle, and before acid rinse.

rinsing water
 * a. Water used to remove fine particles from larger sizes, usually located over vibrating screens.

b. Syn: spray water.

Rio Tinto process
 * Heap leaching of cupriferous sulfides after their slow oxidation to sulfates on prolonged atmospheric weathering.

rip
 * a. To bring down rock in a roadway to increase headroom. See also: dint.

b. See: brush.

riparian
 * a. Pertaining to or situated on the bank of a body of water, esp. of a watercourse such as a river; e.g., riparian land situated along or abutting upon a stream bank, or a riparian owner who lives or has property on a riverbank.

b. Pertaining to shrubs and trees with root systems that seek deep ground water, as mesquite and greasewood.

riparian rights
 * The rights of a person owning land containing or bordering on a watercourse or other body of water in or to its banks, bed, or waters. Under common law, a person owning land bordering a nonnavigable stream owns the bed of the stream and may make reasonable use of its waters.

rip current
 * A strong surface current of short duration flowing seaward from the shore. It usually appears as a visible band of agitated water and is the return movement of water piled up on the shore by incoming waves and wind. Syn: rip tide. CF: undertow.

rippability
 * A measure of the ease or difficulty with which a rock or earth material can be broken by tractor-drawn rippers or rigid steel tines into pieces that can be economically moved by other equipment, usually scrapers.

ripper
 * a. Coal miner who breaks down the roof of a gate road to increase headroom or breaks down the roof at the ripping lip, or where the roof has sagged on a roadway due to subsidence. The miner is often paid on yardage of ripping performed. Also known as brusher; stoneman; repairer. See also: trenchman; stoneman.

b. A tool for removing slates, or edging them. c. An accessory that is either mounted or towed at the rear of a tractor and generally used in place of blasting as a means of loosening compacted soils and soft rocks for scraper loading. The ripper has long, angled teeth that are forced into the ground surface, ripping the earth loose to a depth of 2 ft (0.6 m) or more. d. See: rooter.

ripping
 * a. A machine for cutting stone into slabs by passing it on a bed under a gang of saws.

b. The act of breaking, with a tractor-drawn ripper or long-angled steel tooth, compacted soils or rock into pieces small enough to be economically excavated or moved by other equipment such as a scraper or bulldozer. c. The breaking down of the roof in mine roadways to increase the headroom for haulage, traffic, and ventilation. See also: brushing; second ripping.

ripping bed
 * A machine for cutting stone into slabs by passing it on a bed under a gang of saws.

ripping blasting
 * Where coal seams are worked by the longwall method it is necessary to maintain roadways leading to the face. These roadways should be of sufficient height to permit the easy passage of workers and materials, and this invariably means that some of the stone above the coal must be removed. This operation is known as ripping, and, unless the roof strata are very soft, blasting will be required. The main considerations in ripping blasting are to keep the sides of the roadway square, and to obtain good fragmentation of the stone so that it can be removed easily.

ripping face support
 * A timber, or timber and steel structure, to provide support at the ripping lip. There are various types: one consists of bent corrugated steel bars behind which wooden planks are wedged; another consists of adjustable stretchers that are fitted across the roadway. See also: roadhead.

ripping lip
 * a. The edge of the rippings at the face of a roadway. When enlarging a roadway, the ripping lip is the end of the enlarged section and where work is proceeding. See also: forepoling girder.

b. The edge of the nether roof at a gate end at the point up to which the ripping has been taken.

ripping scaffold
 * A staging or platform erected over the moving conveyor at a ripping lip of a gate road, on which the miners can stand and work. This implies that the coalface and conveyor loading point are some distance ahead.

rip plates
 * A means of repairing damaged belting. It consists of two short plates, with teeth on one side to grip the belting, which are fastened on both sides of the belting across the rip or worn place. Short bolts and nuts serve to compress and hold the plates tightly against the belting.

ripple
 * A groove or bar across sluices for washing gold. See also: riffle.

ripple board
 * An inclined trough having grooves or strips across its bottom to catch fine gold. See also: riffle.

ripple index
 * The ratio of wavelength to amplitude of a ripple mark. It usually ranges from 6 to 22 for ripples produced by water currents or waves and from 20 to 50 for ripples produced by wind. Syn: ripple-mark index.

ripple mark
 * a. An undulatory surface or surface sculpture consisting of alternating subparallel small-scale ridges and hollows formed at the interface between a fluid and incoherent sedimentary material (esp. loose sand). It is produced on land by wind action and subaqueously by currents or by the agitation of water in wave action, and generally trends at right angles or obliquely to the direction of flow of the moving fluid. It is no longer regarded as evidence solely of shallow water.

b. One of the small and fairly regular ridges, of various shapes and cross sections, produced on a ripple-marked surface; esp. a ripple preserved in consolidated rock and useful in determining the environment of deposition. The term was formerly restricted to symmetrical ripple mark, but now includes asymmetrical ripple mark. The singular form may be used to denote general ripple structure (as well as a specific ripple), and the plural form to describe a particular example.

ripple-mark index
 * See: ripple index.

ripple voltage
 * The alternating component of a substantially unidirectional voltage.

riprap
 * a. A layer of large, durable fragments of broken rock, specially selected and graded, thrown together irregularly (as offshore or on a soft bottom) or fitted together (as on the upstream face of a dam). Its purpose is to prevent erosion by waves or currents and thereby preserve the shape of a surface, slope, or underlying structure. It is used for irrigation channels, river-improvement works, spillways at dams, and sea walls for shore protection.

b. The stone used for riprap.

rip tide
 * See: rip current.

rise
 * a. A vertical or inclined shaft from a lower to an upper level in a mine. See also: upraise; raise.

b. To dig upward, as from one level to the next one above; opposite of sink. c. Upward inclination of a coal stratum. d. An ascending gallery at the end of a level. See also: hade.

rise and fall
 * A system of reduction of levels by working out the rise or fall of staff readings from each level point to the one following it. See also: collimation.

rise face
 * A face advancing toward the rise of a coal seam.

rise heading
 * A heading driven to the rise in a long-way workings. See also: heading.

riser
 * a. A shaft excavated from below upward. See also: raise; rise.

b. See: column pipe; rising main.

rising
 * a. An excavation carried from below upward; a rise or riser.

b. Eng. The horizontal division of the stratum, from which the blocks of stone are lifted; e.g., in the Portland quarries.

rising column
 * See: rising main.

rising current
 * The direction in which a drill circulation fluid is flowing after it has passed the bit and continues toward the collar of a borehole.

rising-head test
 * A soil permeability test in which the level of water in a borehole is reduced and then the rate at which the water recovers is observed.

rising main
 * a. The length of steel piping that conveys the water from a pump to the surface or to a higher pump in the shaft. The term rising main is obsolete; delivery column preferred. Syn: delivery column.

b. See: column pipe.

rising shaft
 * Excavating a shaft upwards from mine workings. See also: rise; staple shaft.

rittingerite
 * See: xanthoconite.

Rittinger's law
 * The energy required for reduction in particle size of a solid is directly proportional to the increase in surface area. CF: Kick's law.

Rittinger table
 * A side-bump table with plane surface, actuated by a cam, spring, and bumping post.

rivelaine
 * A pick with one or two points, formed of flat iron, used to undercut coal by scraping instead of striking.

river bar
 * A ridge or mound of boulders, gravel, sand, and mud found along or in a stream channel at places where decrease in velocity causes deposition of sediment.

river-bar placer
 * a. Gravel flats and terraces laid down by rivers when flowing at higher levels than at present. The deposits are sometimes gold or tin-bearing. See also: bench placer.

b. A term used in Alaska for placers on gravel flats in or adjacent to the beds of large streams.

river claim
 * A claim that includes the bed of a river.

river drift
 * The gravel deposits accumulated by a river in its torrential stages.

river flat
 * See: alluvial flat.

river mining
 * Mining or excavating beds of existing rivers after deflecting their course, or by dredging without changing the flow of water.

river pebble
 * Applied in Florida to a certain class of phosphatic pebbles, or concretions, found in rivers as distinguished from land pebble phosphate.

river plain
 * See: alluvial plain.

river quartz
 * Rounded, waterworn masses of quartz found in stream gravels.

river right
 * See: creek right.

river run gravel
 * Natural gravel as found in deposits that have been subjected to the action of running water. See also: alluvial deposit.

river sand
 * Sand generally composed of rounded particles, and may or may not contain clay or other impurities. It is obtained from the banks and beds of rivers.

rives in
 * Eng. To crack open or produce fissures.

rivet
 * A round bar of mild steel having a conical, cup- or pan-shaped head, which is driven while red hot into a hole through two plates of steel that have to be joined together. Aluminum, copper, and other materials are also used for rivets. See also: pneumatic riveter.

riveter
 * A worker who forms the head of a rivet, generally with a pneumatic rivet hammer.

rivet forge
 * A portable forge, used by boilermakers and ironworkers, for heating rivets near the work for which they are required.

rivet heater
 * A laborer responsible for heating rivets in a portable forge and throwing them with tongs to the rivet catcher.

rivet snap
 * A punch having a recess in its head shaped to the form of the rivet. See also: pneumatic riveter.

rivet test
 * A test on the steel used for rivets, in which a bar is bent through 180 degrees ; if any cracks are formed, the steel is rejected.

rivet tester
 * A trained worker who can detect sound or loose rivets by testing them with a hammer.

riving seams
 * Open fissures between beds of rock in a quarry.

R.K. process
 * A method for converting pig iron into a product with a low carbon content, which is suitable as a substitute for steel scrap for remelting in steel furnaces.

road
 * a. A roadway in a mine, e.g., gate road, traveling road, dummy road.

b. Any mine passage or tunnel. c. Rail track.

roadbed
 * a. The material fundamental part of a road; primarily, the foundation of gravel, road metal, etc., constituting the bed, but by extension, esp. in railway use, the superstructure also.

b. The foundation carrying the sleepers, rails, chairs, points, and crossings, etc., of a railway track.

road cleaner
 * See: track cleaner.

road dust
 * Dust found on the floor of a mine entry.

roadhead
 * The face of a roadway, usually in longwall conveyor mining. The records indicate that the roadhead is the most dangerous place in a coal mine based on accidents from falls of ground. See also: ripping face support.

road-making plant
 * Various types of specialized plant used solely for road construction, including such machines as planers, scarifiers, rollers, pavers, finishers, gritters, and mixers.

roadman
 * a. A person employed on the laying and maintenance of rail tracks underground. Also known as a trackman.

b. A person whose duty it is to keep the roads of a mine in order. c. In bituminous coal mining, a general term for miners working along haulageways or airways (roads). Usually designated according to job, as repairman; wasteman.

road metal
 * Crushed stone for surfacing macadamized roads, and for the base course of asphalt and concrete roadways; also used without asphaltic binder as the traffic-bearing surface, generally on secondary roads.

road-mix method
 * A method of preparing aggregates for bituminous surfaces in which the aggregates and bitumen are combined on the surface of the road, using the penetration or mixed-in-place method.

road roller
 * Power-driven roller of any weight from one-half to 12 tons.

roadside pack
 * A pack built alongside a roadway. See also: rib-side pack.

roadster
 * Low-priced model of a scraper or a truck.

roadway
 * An underground drivage. It may be a heading, gate, stall, crosscut, level, or tunnel and driven in coal, ore, rock or in the waste area. It may form part of longwall or bord-and-pillar workings or an exploration heading. A roadway is not steeply inclined. See also: roadway support.

roadway cable
 * An electric cable designed for use in mine roadways. It may be either rubber insulated, sheathed, and armored or paper insulated.

roadway consolidation
 * To bind the floor dust together with water and calcium chloride flakes, or other chemical, to form a firm plastic carpet. See also: dust consolidation.

roadway support
 * A timber, steel, concrete, or other erection in a roadway to (1) ensure safety by preventing falls of ground, and (2) maintain the maximum possible roadway size by resisting the tendency of the roadway to contract and distort. See also: steel arch; roadway.

roast
 * To heat to a point somewhat short of fusing, with access of air, as to expel volatile matter or effect oxidation.

roaster
 * A reverberatory furnace or a muffle used in roasting ore.

roaster slag
 * Slag resulting from the calcination of white metal in the process of copper smelting.

roasting
 * a. Heating an ore to effect some chemical change that will facilitate smelting.

b. The operation of heating sulfide ores in air to convert to oxide or sulfate. c. Calcination, usually with oxidation. Good, dead, or sweet roasting is complete roasting; i.e., it is carried on until sulfurous and arsenious fumes cease to be given off. Kernel roasting is a process of treating poor sulfide copper ores, by roasting in lumps, whereby copper and nickel are concentrated in the interior of the lumps. d. The heating of solids, frequently to promote a reaction with a gaseous constituent in the furnace atmosphere. See also: magnetizing roast.

roasting and reaction process
 * The treatment of metal ore in a reverberatory, by first partly roasting at a low temperature and then partly fusing the charge at a higher temperature, which causes a reaction between the lead oxide formed by roasting and the remaining sulfide, producing sulfurous acid and metallic lead. Syn: air-reduction process.

roasting and reduction process
 * The treatment of lead ores by roasting to form lead oxide, and subsequent reducing fusion in a shaft furnace.

roasting cylinder
 * A furnace with a rotating cylinder for roasting, amalgamating, or smelting ore. See also: Bruckner furnace.

roasting furnace
 * A furnace in which finely ground ores and concentrates are roasted to eliminate sulfur or other elements or compounds; heat is provided by the burning sulfur. The essential feature is free access of air to the charge, by having a shallow bed that is continually rabbled. Many types have been devised; multiple hearth is the most widely used.

roast sintering
 * See: blast roasting.

rob
 * A form of roasting furnace, built in compartments or stalls open in front, with flues running up the wall at the back for the purpose of creating a draft. �Q �k �k �K5��       � � DICTIONARY TERMS:rob To extract mine pillars previously left for sup To extract mine pillars previously left for support, often preparatory to closing a mine. Syn: second mining.

robber
 * a. In anthracite and bituminous coal mining, one who breaks down and rips out with a pick, pillars of coal left to support the roof in rooms when the usual mining was being done. Also called pillar robber.

b. An extra cathode or cathode extension that reduces the current density on what would otherwise be a high current-density area on the work.

robbing
 * a. Removing timber from a mined-out stope to use it again elsewhere.

b. Extraction of the pillars of ore left to support workings during original stoping. c. Scot. Reducing the size of pillars; taking as much as possible off pillars, leaving only what is deemed sufficient to support the roof.

robbing an entry
 * See: drawing an entry.

robbing pillars
 * The mining of coal pillars left to support the roof during development mining, often resulting in cave-ins. See also: working the broken.

Robiette process
 * A heat treatment process carried out in a substantially closed furnace, in which a fluid fuel is burnt to partial combustion with a gas containing 70% or more of oxygen to produce a nonoxidizing atmosphere. The treatment is effected continuously in the furnace through which the heating gas and metal are passed in opposed directions. The fuel and gas are partially burnt at the exit end of the furnace, and passed to the cooler entry end of the furnace, and burnt to substantially complete combustion so as to preheat metal entering the furnace.

Robins-Messiter system
 * A stacking conveyor system in which material arrives on a conveyor belt and is fed to one or two wing conveyors. This part of the system moves so as to form a long ridge; reclaimed by raking gear that works across the ridge, moving slowly forward and shifting material loosened and blended by the rake action by means of a spiral that pushes it to a reclaiming conveyor at the side of the ridge. Used to stockpile ore, concentrates, and coal.

Robinson and Rodger system
 * A method of obtaining sound steel by fluid compression of the ingot in the mold. The molds are divided in the center, a removable packing piece being placed between the halves of the mold. The packing piece is removed when the metal has set, and the mold is placed horizontally in the press, pressure being applied to the ingot at both ends.

robinsonite
 * A triclinic mineral, Pb (sub 4) Sb (sub 6) O (sub 13).

robot loader
 * A pneumatic loader for inserting cartridges into drill holes.

Robson and Crowder process
 * An early oil flotation process. The oil was added to several times its weight of ore and mixed in a slowly revolving drum or tube. The process at one time had quite a large application. The process used but little water (25% to 30%) and no acid.

Roburite
 * Smokeless and flameless safety explosive consisting of ammonium nitrate and dinitrobenzene or dinitrochloro benzene; used in mines.

roca
 * a. Sp. Rock or stone, whether in the ordinary or geological sense.

b. Sp. Rock standing out from the general surface. c. Sp. A vein or bed of hard rock and stone.

roche
 * Fr. Rock, boulder.

rock
 * a. An aggregate of one or more minerals, e.g., granite, shale, marble; or a body of undifferentiated mineral matter, e.g., obsidian, or of solid organic material, e.g., coal.

b. Any prominent peak, cliff, or promontory, usually bare, when considered as a mass, e.g., the Rock of Gibraltar. c. A rocky mass lying at or near the surface of a body of water, or along a jagged coastline, esp. where dangerous to shipping. d. A slang term for a gem or diamond. e. Strictly, any naturally formed aggregate or mass of mineral matter, whether or not coherent, constituting an essential and appreciable part of the Earth's crust. Ordinarily, any consolidated or coherent and relatively hard, naturally formed mass of mineral matter; stone. In instances, a single mineral forms a rock, as calcite, serpentine, kaolin, and a few others but the vast majority of rocks consist of two or more minerals. f. A local term used in New York and Pennsylvania for the more massive beds of bluestone that are not jointed and are, therefore, well-suited for structural purposes. g. In the geological sense, any natural deposit or portion of the Earth's crust whatever be its hardness or softness, but used by miners to denote sandstone. h. In geology, the material that forms the essential part of the Earth's solid crust, and includes loose incoherent masses, such as a bed of sand, gravel, clay, or volcanic ash, as well as the very firm, hard and solid masses of granite, sandstone, limestone, etc. Most rocks are aggregates of one or more minerals, but some are composed entirely of glassy matter, or of mixtures of glass and minerals. i. In the Lake Superior region, crude copper ore as it comes from the mines. The concentrate obtained is called mineral, and contains about 65% metallic copper.

rock asphalt
 * See: asphalt rock.

rock association
 * a. A group of igneous rocks within a petrographic province that are related chemically and petrographically, generally in a systematic manner such that chemical data for the rocks plot as smooth curves on variation diagrams. See also: tribe. Syn: rock kindred; kindred; association.

b. The association of mineral deposits with certain rock types. If mineral-producing localities are considered individually, valuable generalizations often can be made, and lithotectonic-plate tectonic classifications of ore deposits and exploration strategies derived from them.

rock base
 * See: bedrock.

rock bit
 * a. Any one of many different types of roller or drill bits used on rotary-type drills for drilling large-size holes in soft-to-medium-hard rocks; also sometimes applied to drag-type bits. See also: drag bit; roller bit.

b. In mining, a detachable-type chisel or cruciform bit used on percussive drills to drill small-diameter holes in rock. c. See: drill bit.

rock body
 * A dump body with oak planking set inside a double steel floor.

rock bolt
 * A bar, usually constructed of steel, that is inserted into pre-drilled holes in rock and secured for the purpose of ground control. Rock bolts are classified according to the means by which they are secured or anchored in rock. In current usage there are mainly four types: expansion, wedge, grouted, and explosive. See also: roof bolt.

rock bolting
 * a. See: roof bolting.

b. The process of rock bolting consists of (1) anchoring the bolt in a hole; (2) applying tension to the bolt to place the rock under compression parallel to the bolt; and (3) placing the bolts in such a pattern that they will properly support the rock structure. Rock may be supported by bolts in five ways: (1) suspension; (2) beam building; (3) reinforcement of arched opening requiring support; (4) reinforcement of an opening otherwise self-supporting; and (5) reinforcement of walls against shear and compressive action. See also: roof bolting.

rockbridgeite
 * An orthorhombic mineral, (Fe,Mn)Fe (sub 4) (PO (sub 4) ) (sub 3) (OH) (sub 5) ; forms a series with frondelite; dark green; named for Rockbridge County, VA.

rock bump
 * The sudden release of the weight of the rocks over a coal seam or of enormous lateral stresses due to structural or tectonic folds and thrusts and sometimes both. A rock bump may take the form of a pressure bump or a shock bump.

rock burst
 * A sudden and often violent breaking of a mass of rock from the walls of a tunnel, mine, or deep quarry, caused by failure of highly stressed rock and the rapid or instantaneous release of accumulated strain energy. It may result in closure of a mine opening, or projection of broken rock into it, accompanied by ground tremors, rockfalls, and air concussions. See also: burst; pressure bump.

rock butter
 * A soft yellowish mixture of alum with aluminum and iron oxides; a decomposition product of aluminous rocks. See: stone butter.

rock car runner
 * See: car runner.

rock channeler
 * A machine used in quarrying for cutting an artificial seam in a mass of stone. It is made in several forms, the principal types being the bar channeler (in which the cutters are mounted on a carriage that works along a heavy bar or bars) and the track channeler.

rock chute
 * See: chute; rock hole. Also called slate chute.

rock-chute mining
 * See: bord-and-pillar method.

rock cleavage
 * The property or tendency of a rock to split along closely spaced planar structures, produced by deformation or metamorphism. See also: schistosity.

rock cone bit
 * See: roller bit.

rock contractor
 * In anthracite coal mining, one who contracts to mine rock, as distinguished from coal, at a certain price per ton or footage of advance.

rock cork
 * A light-colored variety of asbestos. Syn: mountain cork; rock leather.

rock cover
 * Thickness of consolidated rock above the roof of an opening (equivalent to cover, minus depth of weathering or of other soil). CF: cover.

rock crusher
 * A machine for reducing rock or ore to smaller sizes. Three principal types are the jaw crusher, the gyratory, and the hammer crusher.

rock crystal
 * a. Transparent quartz.

b. Highly polished brown glassware, hand-cut or engraved.

rock cut
 * A way, esp. for a railroad, cut through a rock or rocky formation.

rock cuttings
 * See: cuttings; sludge.

rock cycle
 * A sequence of events involving the formation, alteration, destruction, and reformation of rocks as a result of such processes as magmatism, erosion, transportation, deposition, lithification, and metamorphism. A possible sequence involves the crystallization of magma to form igneous rocks that are then broken down to sediment as a result of weathering, the sediments later being lithified to form sedimentary rocks, which in turn are altered to metamorphic rocks.

rock dredge
 * a. A dredge that excavates rock for the purpose of deepening harbors and waterways; also, a device for sampling underwater outcrops and boulders.

b. A general term for a seabed sampling device consisting of a heavy bucket frame that is pulled across the seabed on a cable controlled by a winch operator on deck.

rock drift
 * A horizontal mine passage cut in rock, esp. along a vein on a principal level of a mine. See: crosscut; stope.

rock drill
 * a. A machine for boring relatively short holes in rock for blasting purposes. It may be a sinker, jackhammer, drifter, or stoper. See also: percussive drill; rotary drill. Syn: Waugh drill.

b. A roller bit. c. A conical bit for drilling hard rock.

rock-drill bit
 * See: rock bit.

rock driller
 * a. In bituminous coal mining, one who works in rock or slate as distinguished from coal. Also called rock shooter; slate driller.

b. See: rock splitter.

rock drivage
 * A hard heading or stone drift.

rock dust
 * a. The general name for any kind of inert dust used in rendering coal dust inert or in filling rock-dust barriers. Equivalent to the British stone dust.

b. The dust produced in mines by blasting, drilling, shoveling, and handling rock. Rock dust in suspension varies in particle size and composition. The most dangerous dusts are silica, sericite, and asbestos; but all fine dusts are health hazards when inhaled. The smaller sizes, 10 microns and less, are more dangerous than the larger sizes. Wet drills, sprays, water infusion, and ample ventilation are employed to reduce the dust menace. See also: dust consolidation; dust-free conditions; stone dust; stone-dust barrier.

rock-dust barrier
 * a. A device that releases a large quantity of inert dust in the air in the path of an explosion, extinguishing the flame.

b. A series of troughs or shelves laden with rock dust and so arranged that the air waves from an explosion will trip them and fill the air with rock dust and thus quench the flame of exploding coal dust.

rock duster
 * a. A machine that distributes rock dust over the interior surfaces of a coal mine by means of air from a blower or pipeline or by means of a mechanical contrivance, to prevent coal dust explosions. Also called rock-dust machine.

b. See: rock-dust man.

rock dusting
 * a. The dusting of underground areas with powdered limestone to dilute the coal dust in the mine atmosphere and on the mine surfaces, thereby reducing explosion hazards.

b. A very widespread control measure used in coal mines to combat explosive dusts. By machine, inert (combustible) dust is sprayed, dry or wet, on the roof, floor, and ribs in all working places and haulageways, to reduce the explosibility of settled coal dust. The Mine Safety and Health Administration requires rock dusting to within 40 ft (12 m) of the face. The incombustible content of settled dust samples after rock dusting must constitute 65% or more by weight, with an increase of 1% for each 0.1% methane present. A dust as nearly inert, physiologically, as possible, should be employed in rock dusting; limestone (calcium carbonate) is most widely used.

rock-dusting machine
 * A machine consisting essentially of a flexible hose fed by a powerful blower. It is used in forcing rock dust, usually powdered limestone, onto the floor, walls or ribs, and rooms and entries of a mine, thereby making the coal dust nonexplosive.

rock-dust man
 * In bituminous coal mining, a laborer who sprinkles rock dust by hand or with a machine throughout mine workings as a precaution against explosions. Syn: rock duster. Also called rock-dust sprinkler.

rock-dust testing kit
 * This kit is designed to prevent coal-dust explosions. It helps to determine the explosion hazard prior to rock dusting, the fineness of the rock dust as it comes from the pulverizer, and the percentage of combustible matter present in rock and coal dust mixtures after rock dusting.

rock-dust zone
 * A section of a mine entry, the ribs, roof, and floor of which have been coated with rock dust.

rocker
 * a. A small digging bucket mounted on two rocker arms in which auriferous alluvial sands are agitated by oscillation, in water, to collect gold. A shortened term for rocker shovel; rocker arm shovel.

b. Used for testing placer deposits and for working pockets and small placer deposits. The gold-bearing gravel is placed on the screen; gold and fine sand are washed through the screen, and remaining stones are cleaned out. A chute directs the material to the upper end of the bottom, which may be covered with small transverse riffles or canvas. Waste material passes over a tailpiece at the end of the rocker. Rockers range in length from 6 to 12 ft (2 to 4 m), and in bottom width from 14 to 20 in (35 to 50 cm), with holes in the screens from 1/4 to 1/2 in (0.6 to 1.2 cm) in diameter. The slope of the rock should be adjusted to the nature of the gravel and is commonly 1 in 12, ranging from 1 in 8 to 1 in 20. Two workers with a rocker can handle from 3 to 5 yd (super 3) (2.3 to 3.8 m (super 3) ) of gravel in place in 10 h if the ground is easily rocked. c. A portable sluicebox used by prospectors and fossickers in treating alluvial mineral deposits. Also called rocking cradle.

rocker arm
 * a. A lever resting on a curved base so that the position of its fulcrum moves as its angle changes.

b. A bell crank with the fulcrum at the bottom.

rocker arm shovel
 * See: rocker shovel.

rocker bottom
 * See: rocker.

rocker dump car
 * Among the smaller capacity cars, the most popular and most widely used are the gravity dump types, such as rocker dump and scoop cars, designed so that the weight of the load tips the body when a locking latch is released by hand. The body of this type is balanced to right itself after the load is discharged. Rocker dump cars range in capacity from 1 yd (super 3) (0.76 m (super 3) ) handloaded types, to units of 10 yd (super 3) (7.6 m (super 3) ) for power shovel loading.

rocker shovel
 * A digging and loading machine consisting of a bucket attached to a pair of semicircular runners that when rolled, lifts and dumps the bucket load into a car or other materials transport unit behind the machine.

rocker sieve
 * A miner's cradle or rocker, a cradlelike device for washing out mud from the contents of a dredge.

rock excavation
 * In situ removal of all firm, unaltered, and unweathered surface geological materials.

rock fabric
 * See: fabric.

rock factor
 * See: resistance to blasting.

rock failure
 * Fracture or failure of a rock that has been stressed beyond its ultimate strength.

rockfall
 * a. The relatively free falling or precipitous movement of a newly detached segment of bedrock (usually massive, homogeneous, or jointed) of any size from a cliff or other very steep slope; it is the fastest form of mass movement and is most frequent in mountain areas and during spring when there is repeated freezing and thawing of water in cracks in the rock. Movement may be straight down, or in a series of leaps and bounds down the slope; it is not guided by an underlying slip surface.

b. The mass of rock moving in or moved by a rockfall; a mass of fallen rocks. Also spelled rock fall.

rock fault
 * Eng. A replacement of a coal seam over a greater or lesser area by some other rock, usually sandstone. See also: horse; washout.

rock-fill dam
 * An earth dam built of any broken rock or similar material that may be available.

rock filling
 * a. Waste rock, used to fill up worked-out stopes to support the roof.

b. See: overhand stoping.

rock flour
 * a. Powdered rock material formed by the grinding-up of rocks beneath a glacier, either deposited as part of the till or washed or blown away and deposited elsewhere as stratified drift or loess. Also called glacier meal. Syn: rock meal. See also: silt.

b. Fault gouge.

rock flow
 * a. The movement of solid rock when it is in a plastic state.

b. The term given to a slope failure when there is a general breakdown of the rock mass. When such a rock mass is subjected to shear stresses sufficient to break down the cement or to cause crushing of the angularities and points of the rock blocks, the blocks will move as individuals and the mass will flow down the slope, or will slump into a more stable slope position.

rock formation
 * See: formation.

rock-forming mineral
 * A mineral that is common and abundant in the Earth's crust; one making up large masses of rock. From 20 to 30 minerals are usually considered as being the most important.

rock foundation
 * A foundation that is carried down to the solid rock. The rock is cut and dressed level, loose and decayed portions are removed, and holes filled with concrete. The crushing strength of the rock can be ascertained by tests and the bearing pressure should not exceed one-eighth of the value.

rock fracture
 * When rock is broken by crushing or impact, the resulting fragments can be divided into two components: (1) the complement, comprising a wide size distribution in accordance with a probability law, and (2) the residue of large incompletely broken pieces. The relative proportions of complement and residue depend upon the mode of fracture. If the rock is completely crushed, only complement is formed, but if the rock is fractured by the impact of a point or wedge, there may be more residue than complement. Syn: complement.

rock glacier
 * An ice-cored mass of angular rock waste, usually heading in a cirque or other steep-walled amphitheater and in many cases grading into a true glacier.

rock glass
 * Obsidian or other volcanic glass.

rock gypsum
 * A massive, coarsely crystalline to finely granular, sedimentary rock of the mineral gypsum with bedding commonly disturbed by expansion during hydration of parent anhydrite. Syn: gyprock.

rock hardness
 * The resistance of the rock to the intrusion of a foreign body.

rockhead
 * a. The upper surface of bedrock.

b. The boundary between superficial deposits (or drift) and the underlying solid rock. c. See: bedrock.

rock hole
 * A short staple shaft driven from a lower to a higher coal seam and used for the gravity transfer of coal to the haulage road in the lower seam. See also: roofing hole. Syn: rock chute.

rock hound
 * An amateur mineralogist or collector.

rocking
 * a. The process of separating ores by washing on an incline trough. See also: rocker.

b. Pushing a resistant object repeatedly, and backing or rolling back between pushes to allow it to reach or cross its original position.

rocking beam
 * See: walking beam.

rocking cradle
 * Short sluice, hand-oscillated; used in gold prospecting and fossicking. See also: rocker.

rocking lever
 * A beam to give the reciprocal motion in hand boring.

rock kicker
 * Usually found at sand and gravel processing facilities. A mechanical device consisting of a roller (with rows of metal protrusions along its length) placed at a 45 degrees angle just ahead of a feed hopper (or conveyor transfer point). It is usually run by a small electric motor and as roots, large stones, and clay meet the roller, they are dumped off the belt to a small pit that is periodically cleaned out.

rock kindred
 * See: rock association.

rock leather
 * See: mountain leather.

rock loader
 * a. Any device or machine used specif. for loading slate or rock inside a mine. However, it is most frequently used with scraper loaders equipped for handling rock. Syn: rock-loader operator.

b. See: box loader.

rock-loader operator
 * See: rock loader.

rockman
 * In bituminous coal mining, a foreman who is in charge of the drilling of holes in rock or slate and the charging and tamping of explosives in the holes drilled by miners prior to blasting. See also: slateman.

rockman helper
 * See: slate-shooter helper.

rock meal
 * See: rock flour.

rock mechanics
 * a. Mathematical analysis of the forces acting along joints, faults, and bedding planes of natural rock in situ, esp. in the evaluation of wall strengths, and hence slopes and slope ratios, in open-pit mines.

b. The theoretical and applied science of the physical behavior of rocks, representing a branch of mechanics concerned with the response of rock to the force fields of its physical environment (NAS-NRC, 1966).

rock melt
 * A liquid solution of rock-forming mineral ions at sufficiently high temperatures to be considered molten.

rock milk
 * Soft pulverulent forms of calcite found in caves, or as an efflorescence. See: agaric mineral.

rock miner
 * In anthracite and bituminous coal mining, a miner who works in rock as distinguished from coal.

rock navvy
 * A cranelike loading machine used at opencast pits and quarries. See also: power shovel.

rock pedestal
 * See: pedestal.

rock phosphate
 * See: phosphate rock.

rock pillar
 * See: hoodoo.

rock pressure
 * a. The pressure exerted by surrounding solids on the support system of underground openings, including that caused by the weight of the overlying material, residual unrelieved stresses, and pressures associated with swelling clays.

b. The compressive stress within the solid body of underground geologic material. c. See: ground pressure; geostatic pressure. d. In petroleum geology, the pressure under which fluids, such as water, oil, and gas, are confined in rocks. No particular cause or origin of the pressure is implied. Geophysicists and isostasis, however, have used, and are using, the term rock pressure in the primitive and more correct sense of the pressure exerted on underlying rock by superincumbent strata. To avoid confusion, it is desirable to substitute for the term rock pressure, as now used in oil, gas, and underground water technology, the more appropriate term reservoir pressure.

rock pressure burst
 * A sudden and violent failure of rock masses under stresses exceeding the elastic strength of the rock. The classification and nomenclature of these  occurrences are not clear and are based largely on effects and not on the basic causation factor. See also: pressure bump; rock bump; rock burst.

rock quartz
 * Ordinary crystalline quartz. Also called rock crystal.

rock rake
 * A heavy duty rake blade.

rock roll
 * Inverted ridges of rock, usually sandstone, extending from the overlying strata into a coal seam, caused by localized streams active during the formation of the coal. See also: classical washout.

rock ruby
 * A fine red variety of pyrope garnet. See also: pyrope.

rock salt
 * Coarsely crystalline halite, NaCl, resulting from evaporation of saline water; in massive, fibrous, or granular aggregates; occurs as a nearly pure sedimentary rock, as extensive beds, or in domes or plugs. See also: common salt; salt.

rock sediment
 * The combined cuttings and residue from drilling and sedimentary rocks and formations, commonly known as sand pumpings.

rock series
 * See: igneous-rock series.

rockshaft
 * A shaft made for sending down rock for filling the stopes, etc., generally kept nearly full, the rock being trammed away as needed.

rock sharp
 * A mineral expert.

rock shovel
 * A machine for loading broken rock. See also: shovel loader.

rock silk
 * A silky variety of asbestos.

rockslide
 * a. A slide involving a downward and usually sudden and rapid movement of newly detached segments of bedrock sliding or slipping over an inclined surface of weakness, as a surface of bedding, jointing, or faulting, or other preexisting structural feature. The moving mass is greatly deformed and usually breaks up into many small independent units. Rockslides frequently occur in high mountain ranges, as the Alps or Canadian Rockies.

b. The mass of rock moving in or moved by a rockslide. Also spelled rock slide. Syn: rock slip.

rock slip
 * See: rockslide.

rock slope
 * A slope driven through rock strata.

rock soap
 * See: mountain soap.

rock spar
 * Material filling fracture cleavages in coal, consisting of nonclay mineral matter, probably deposited from solution, and sand, usually calcite or gypsum.

rock splitter
 * In the stonework industry, one who splits large blocks of building granite, marble, and sandstone into slabs or smaller blocks, by drilling holes into the stone and then driving wedges into them until the stone breaks along the line of drilled holes. Also called rock breaker; rock driller. See also: rock driller; quarryman.

rock stress
 * a. See: rock pressure.

b. The problem of determining the stresses that exist in the Earth's crust has long been of interest to engineers and geologists. Many mining problems are directly concerned with stresses that may cause mine openings to collapse. Two phases of occurrence of rock stresses are important: (1) the stresses existing in the rock before the excavation of the mine openings; i.e., the free field stress, and (2) the indirect stresses caused by the mine openings. See also: free field stress.

rock temperature
 * a. The formational temperature at depth. The rate of increase of temperature with depth (the geothermal gradient) is highly variable over the earth, but averages 25 degrees C/km.

b. The temperature of the rock in a mine.

rock tunnel
 * A tunnel, drift, or crosscut driven through rock, usually connecting one coalbed with another; also through barren rock in metal mines.

rock turquoise
 * A matrix of turquoise with small grains of turquoise embedded in it.

rock type
 * a. One of the three major groups of rocks: igneous, sedimentary, metamorphic.

b. A particular kind of rock having a specific set of characteristics. It may be a general classification, e.g., a basalt, or a specific classification, e.g., a basalt from a particular area and having a unique description. c. The megascopically recognizable ingredients of coal rock; i.e., vitrain, clarain, durain, and fusain. See also: banded ingredient.

rock waste
 * See: debris.

rock weight
 * S. Afr. One (short) ton (0.9 t) of rock in place equals about 12 ft (super 3) (0.34 m (super 3) ). Horizontally, therefore, the weight of an ore reserve covering a claim over a stoping width of 3 ft (0.91 m) is 64,000 ft (super 2) X 3 ft / 12 ft (super 3) /st = 16,000 st (14,500 t) at 100% payability. In case the vein dips downward, the resulting amount must be divided by the cosine of the angle of dip.

Rockwell hardness test
 * A method of determining the relative hardness of metals and case-hardened materials. The depth of penetration of a steel ball (for softer metals) or of a conical diamond point (for harder metals) is measured. See also: scleroscope hardness test.

Rockwell machine
 * Trade name for an apparatus that measures the hardness of metals and alloys, in which a diamond-pointed cone is pressed under a specific load into the metal. The relative resistance to penetration (Rockwell hardness) is indicated by a number (Rockwell number) on a dial. The operation is called a Rockwell hardness test. Syn: Rockwell tester.

Rockwell tester
 * See: Rockwell machine.

rockwood
 * See: mountain wood.

rock wool
 * See: asbestos.