Appendix:Dictionary of Mining, Mineral, and Related Terms/R/5

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rod bit

A noncoring bit designed to fit a reaming shell that is threaded to couple directly to a drill rod, thus eliminating the core barrel in blasthole drilling. Also called blasthole bit.

rod clearance

See: clearance.

rod coupling

Name for a double-pin-thread coupling used to connect two drill rods together.

rod damp

See: safety clamp.


a. Cleaning and descaling of piping by means of scrapers attached to series of jointed rods.

b. Eng. The operation of fixing or repairing wooden cage guides in shafts. c. In metamorphic rocks, a linear structure in which the stronger parts, such as vein quartz or quartz pebbles, have been shaped into parallel rods. Whether the structure is formed parallel to the direction of transport or parallel to the fold axes has been debated.

rod dope

Grease or other material used to protect or lubricate drill rods. Also called rod grease. Syn: gunk.

rod drag

The rubbing of the rods or drill string on the sidewalls of the borehole. Syn: rod friction.

rod drop

The distance of slump or slag in a long string of rods when released from the drill chuck.

rod elevator

See: elevator; elevator plug.

rod friction

a. The drag created in the flow of the drilling liquid by contact and constrictional effects created by the inside surface of the drill rods and couplings. CF: skin friction; wall friction.

b. See: rod drag.


A massive dense buff to pink rock typically rich in grossular garnet and calcic pyroxene, and enveloped in serpentinite. Epidote, vesuvianite, and other calcium-rich minerals are commonly present. It is formed by metasomatic alteration of a protolith that, in many cases, was a dike rock, as shown by preservation of structures. The name was applied by Bell in 1911.

Rodio-Dehottay process

A method of shaft sinking by the freezing method. It is based on the direct cooling effect of expanding highly compressed carbon dioxide in the freezing pipes. See also: Koch freezing process.


Refers to elongate crystals. CF: acicular; equant; tabular; lathlike.


a. A person who uses or carries a surveyor's leveling rod. Also called rodsman.

b. See: staff man.

rod mill

a. A mill for rolling rod.

b. A mill for fine grinding, somewhat similar to a ball mill, but employing long steel rods instead of balls to effect the grinding.

rod millman

One who grinds clinker, phosphate rock, or ore in a revolving cylinder partially filled with round steel rods; also, he or she tests a product for fineness by observing how much material is left on sieve of determined mesh, and regulates amount of material entering the mill accordingly.


Eng. A rude platform near the shaft's mouth for a night fire.

rod plug

See: elevator plug.

rod proof

A test specimen taken from the melt on an iron rod.

rod pull

a. The number of borehole round trips made in a unit of time.

b. The number of lengths of drill rod (two or more standard 10-ft lengths coupled together and handled and stacked as unit lengths) needed to reach the bottom of the borehole.

rod puller

Various mechanisms, essentially a double-acting air-actuated piston equipped with a rod-gripping device, commonly used to pull drill rods from a borehole in underground workings where a small drill without a hoist is used, or from drill rods stuck in a drill hole. Syn: air rod puller.

rod reaming shell

A reaming shell designed to be coupled directly to a drill rod. See also: rod bit.

rod reducing bushing

A pin-to-box sub used to connect one size rod in a string to a larger or smaller size.

rod reducing coupling

A pin-to-pin adapter used to connect a rod of one size to one of a larger or smaller size.


a. Eng. Vertical or inclined timbers for actuating pumps.

b. Long bars of Swedish iron of the toughest quality, for boring through rocks, etc. c. See: cage guide.

rod sag

The bending of a long drill string due solely to its own weight. Also called rod slack. Syn: sag.

rod shaft

The mine shaft containing the pump rods.

rod shell

See: rod reaming shell.

rod slack

See: rod sag.

rod slap

The impact of drill rods with the sides of a borehole, occurring when the rods are rotating. Syn: whip.

rod snap

A sudden acceleration in rotational speed of the rods followed immediately by a sudden return to the former speed.

rod spear

A long, tapered, four-sided fishing tool. Used to remove a lost drill rod or other tubular piece of drill equipment from a borehole.

rod stand

The length of drill rod handled and stacked in the tripod or derrick as a unit piece during round trips. Also called offtake. See also: double; treble.

rod stock

Round steel rod.

rod string

The drill rods coupled to form the connecting link between the core barrel and bit in the borehole and the drill machine at the collar of the borehole.

rod stuffing box

An annular packing gland fitting between the drill rod and the casing at the borehole collar. It allows the rod to rotate freely but prevents the escape of gas or liquid under pressure. Esp. utilized when drilling with counterflow; when drilling in an area where a high hydrostatic pressure or flow of water may be encountered, as in drilling a cover or pilot hole; or when drilling up holes from an underground drill site.

roentgen equivalent man

A unit of ionizing radiation, equal to the amount that produces the same damage to humans as 1 R of high-voltage X-rays. Abbrev. rem.


See: roentgenite.


A photograph made with X-rays. Syn: roentgenograph; radiograph.


See: roentgenogram.

Roesing lead pump

An automatic apparatus for discharging lead from the kettle; used in the Parkes process.

Roesing wires

Wires suspended in a dust chamber to assist in settling and condensing dust and fumes from furnace gases.

Roesler process

A process for separating copper, and in part silver, from gold by fusing with sulfur or with antimony sulfide, obtaining copper or silver sulfide.


A fine-grained oolite resembling the roe of a fish. See: oolite.

Rohbach solution

An aqueous solution of mercuric barium iodide with a density of 3.5 g/cm (super 3) ; used for separating minerals by density.

Roheisenzunder process

A method that makes use of an airstream at a pressure of 4 atmospheres for atomizing molten pig iron into minute particles. The molten metal falling into an air stream formed by an annular slit in a steel cyclone is atomized, the particles falling into a water bath and subsequently dried.

Rohrbach solution

An aqueous solution of mercuric barium iodide; clear, yellow liquid; very refractive; sp. gr., 3.5. Used in separating minerals by their specific gravity and in microchemical detection of alkaloids.


Prov. Eng. A vein of ore. A variation of rake. See: rake.


a. An elongate protrusion of shale, siltstone, or sandstone (locally limestone) from the roof into a coal seam, causing a thinning of the seam and sometimes replacing it almost entirely. CF: cutout. A roll is commonly overlain by a thin coal stringer.

b. An elongate upheaval of the floor material into a coal seam, causing thinning of the seam. Syn: horseback. c. Various minor deformations or dislocations of a coal seam, such as washouts, small monoclinal folds, or faults with little displacement. d. In veins and other types of ore deposit, a thickening or an arcuate change in dip in the orebody. e. See: roll orebody. f. A rotating cylinder used to support or guide a portion of conveyor belt. g. One of two cylinders or grooved rollers between which material is drawn, for reducing its thickness, as the finished rolls of a rolling mill. h. The appearance of other types of mineral deposits in places where the bed or vein thickens or thins. i. A roughly cylindrical distribution of uranium mineralization occurring usually in the Salt Wash Sandstone. There is some question whether the feature is structural or sedimentary. j. An inequality in the roof or floor of a mine. k. S. Wales. The drum of a winding engine. l. Cast-iron or steel cylinder, used to break coal and other materials into various sizes. Applies to the type of crushing machinery in which the ore or coal is broken between cylindrical rolls, either plain or fitted with steel teeth, revolving toward each other, drawing the material in between the crushing peripheries, which rotate in a vertical plane. m. In powder metallurgy, a machine used to apply pressure progressively to form a compact. See also: crushing roll; ribbed roll; smooth roll; want; washout.

roll compacting

The progressive compacting of metal powders by the use of a rolling mill.

roll crusher

A type of secondary or reduction crusher consisting of a heavy frame on which two rolls are mounted. These are driven so that they rotate toward one another. Rock fed in from above is nipped between the moving rolls, crushed, and discharged at the bottom. See also: double-roll crusher.

rolled metal

Refers to metal, such as silver or stainless steel, which has been clad with a precious metal and rolled to reduce the thickness of the coat.

rolled plate

A thin plate of gold spread upon a layer of base metal by soldering the metals in the bar and then rolling the whole out into plate, forming a thinner plate of gold than that of the ware known as gold-filled. Also called rolled gold.

rolled-steel joist

An I-beam made from a single piece of steel passed through a hot rolling mill.


a. A broad pulley or wheel fixed to the floor, roof, or sides of roadways to prevent a haulage rope running against the ground that would cause excessive friction and wear of rails and sleepers.

b. A component part of a roller chain in which it may serve only to reduce frictional loss occurring as the chain negotiates sprockets. Rollers may also serve as the rolling support for the chain and the load being conveyed. c. A heavy vehicle used for compacting soil, earth fill, and top layers of spoil dumps to increase the density and bearing capacity of the material.

roller bearings

Hard steel cylinders in bearings that have very low frictional resistance.

roller bit

a. A rotary boring bit consisting of two to four cone-shaped, toothed rollers that are turned by the rotation of the drill rods. Such bits are used in hard rock in oil well boring and in other deep holes down to 5,000 m and more. See also: tricone bit; drag bit.

b. A type of rock-cutting bit used on diamond and rotary drills. The bit consists of a shank with toothed, circular, or cone-shaped cutter parts affixed to the head of the bit in such a manner that the cutters roll as the bit is rotated. Generally used for drilling 10-cm-size or larger holes in soft to medium-hard rocks, such as shale and limestone. Usually noncoring and not diamond set. Also called cone bit. CF: noncoring bit. See also: rock bit; roller rock bit. Syn: roller cone bit; roller-cutter bit; rolling cutter bit; toothed roller bit.

roller chain

a. Generally, any sprocket-driven chain made up of links connected by hinge pins and sleeves.

b. Specif., a chain whose hinge sleeves are protected by an outer sleeve or roller that is free to turn.

roller cone bit

See: roller bit.

roller-cone core bit

A type of roller bit with cutter cones arranged to cut an annular ring leaving an uncut section in the center as core.

roller conveyor

A series of rolls supported in a frame over which objects are advanced manually, by gravity or by power. See also: controlled velocity roller conveyor; el conveyor; gravity conveyor; herringbone roller conveyor; hydrostatic roller conveyor; portable conveyor. Syn: gravity roller conveyor.

roller-cutter bit

See: roller bit.

roller gate

Hollow cylindrical crest gate controlling a dam spillway. See also: sector gate; sliding gate.

roller grip

A device for clutching a traction cable between grooved sheaves or rollers.


In mining, a laborer who inspects idler rollers or pulleys over which a cable passes along inclined haulageways, oiling or greasing rollers, resetting displaced ones, and repairing or replacing damaged ones. Also called pulley man; pulley repairer; pulley repairman; roller repairman; sheaveman; wheelman.

roller repairman

See: rollerman.

roller rock bit

A rotary bit fitted with two or more hardened steel or tungsten-carbide-tipped rollers of cylindrical or conical form. Variously known as two-cone bit, three-cone bit, four-cutter bit, etc. See also: roller bit.

roller screen

See: revolving screen.

rolley man

See: incline repairman.

roll feeder

a. A smooth, fluted, or cleated roll or drum that rotates to deliver packages, objects, or bulk materials.

b. A circular drum, plain or ribbed, rotating on a horizontal shaft and situated at the mouth of a bunker or hopper to control the rate of discharge of material therefrom.

roll-front orebody

A roll orebody of the Wyoming type, which is bounded on the concave side by oxidized altered rock typically containing hematite or limonite, and on the convex side by relatively reduced altered rock typically containing pyrite and organic matter. See also: roll orebody.

rolling and quartering

A sampling method in which the sample is formed into the requisite flat heap by placing it upon a rubber or other smooth sheet and, by lifting the corners of this sheet in proper rotation, rolling the material to and fro. The resultant heap is then quartered and alternate quarters are taken. This method is used with smaller bulk and smaller sizes of material.

rolling cradle

A rod slide equipped with rollers that contact the rods and over which the rods roll on being pulled or lowered into an angle borehole.

rolling cutter bit

See: roller bit.

rolling plant

A rolling mill or establishment for rolling metal into forms.

rolling resistance

a. The sum of the external forces opposing motion over level terrain.

b. The tractive resistance caused by friction between the rails and wheels, which forms the major resistance on level tracks. See also: tractive force.

rolling-up curtain weir

A type of frame weir, the frame of which remains upright, being rolled up from the bottom.

roll jaw crusher

A crusher of the same general type as the Blake or Dodge, but the moving jaw has a rolling instead of an oscillating motion.


In beneficiation, one who tends rolls that are used to crush ore, which has already been broken into small pieces in a crusher, to a fine size preparatory to the extraction of the valuable minerals.

roll operator

One who operates conical rolls that separate stone from clay, preventing machine from jamming by regulating flow of clay into it.

roll orebody

A uranium and/or vanadium orebody in a sandstone lens or layer, which cuts across bedding in sharply curving forms, commonly C-shaped or S-shaped in cross section. Two types can be distinguished: the Colorado Plateau type, named in 1956, and the Wyoming type, named in 1962. Roll orebodies of the Colorado Plateau type are of highly variable geometry, with their longest dimension in plan view parallel to the axes of buried sandstone lenses representing former stream channels, and surrounded by a wide halo of reduced (altered) rock. Orebodies of the Wyoming type are crescent-shaped in cross section and typically form in relatively thick, tabular, or elongate sandstone bodies, with the tips of the crescent thinning and becoming tangent to mudstone layers above and below. See also: roll-front orebody.

roll scale

See: mill scale.

roll screen

A screen consisting of a number of horizontal rotating shafts, fitted with elements arranged to provide screening apertures.

roll sulfur

a. A commercial name for sulfur that has been purified and cast into rolls or sticks.

b. See: brimstone.

Roman cement

See: pozzolana cement.


A monoclinic mineral, (Ba,H (sub 2) O)Mn (sub 5) O (sub 10) ; rare as single crystals; commonly intergrown with other manganese oxides. Formerly called psilomelane, a term now reserved for mixtures. CF: hollandite.


A yellow, black, or green amber from Romania. Also spelled rumanite.

Roman ocher

A native ocher of a deep orange-yellow color.

Roman pearl

A hollow sphere of opalescent glass with its interior coated with essence d'orient and then filled with wax.


An isometric mineral, (Ca,Fe,Mn,Na) (sub 2) (Sb,Ti) (sub 2) O (sub 6) (O,OH,F) ; stibiconite group; forms clusters of minute yellow octahedra. Syn: weslienite. See also: atopite.


An instrument for measuring changes in vertical height and lateral movements of the roof relative to the floor at the coal face. Syn: roof movement meter. See also: convergence recorder.


The crust or scale that forms upon the surface of molten metal in cooling.


The unit of exposure dose of X-ray or gamma-ray radiation. One roentgen is an exposure dose of X-ray or gamma-ray radiation such that the associated corpuscular emission per 0.001293 g of air produces, in air, ions carrying 1 electrostatic unit of quantity of electricity of either sign. Designated by the symbol R. Also spelled roentgen.


Minute wax-yellow to brown, trigonal pyramidal crystals, intergrown with synchysite, parisite, and bastnasite, from Narsarsuk, Greenland. From X-ray and optical data, the composition is deduced as Ca (sub 2) (Ce,La) (sub 3) (CO (sub 3) ) (sub 5) F (sub 3) . Also spelled roentgenite.


a. The rock immediately above a coal seam. It is commonly a shale and is often carbonaceous in character and softer than similar rocks higher up in the roof strata. The roof shale may contain streaks and wisps of coaly material, which tends to weaken the deposit. Roof in coal mining corresponds to hanging wall in metal mining. See also: roof stone.

b. In mine timbering there are two classifications of roof, the immediate roof and the main roof. The immediate roof lies directly over the coal and may be a single layer or several layers of rock material of the same, or different consistencies, and from a few inches to several feet in thickness. This roof requires timbering to support it as the coal is removed. The main roof is the roof above the immediate top, and may vary from a few feet to several hundred, or even thousands of feet in thickness. This roof is generally controlled by leaving pillars of solid coal that will support its weight. c. The country rock bordering the upper surface of an igneous intrusion. CF: floor.

roof bolt

a. A long steel bolt inserted into walls or roof of underground excavations to strengthen the pinning of rock strata. It is inserted in a drilled hole and anchored by means of a mechanical expansion shell that grips the surrounding rock at about 4 ft (1 m) spacing and pins steel beams to the roof.

b. Syn: rock bolt. c. Current roof bolting consists of steel rods, 5/8 to 1 in (2 to 2.5 cm) or more in diameter and 3 to 8 ft (1 to 2.5 m) in length, anchored by a mechanical expansion shell, resin grout, or a combination of both. Grouted bolts may be fully or partially grouted. A steel plate, sometimes in combination with wooden headers or steel straps, fits tightly between the bolthead and mine roof or rib.

roof bolter

In bituminous coal mining, one who reinforces roofs of mine haulageways, side drifts, and working places with metal or timber to prevent rock and slate falls. Also called raise driller; stoperman; stoperperson; timberman.

roof bolting

A system of roof support in mines. Boreholes usually from 3 to 12 ft (1 to 4 m) long are drilled upward in the roof, and bolts of 5/8 to 1 in (2 to 2.5 cm) or more in diameter are inserted into the holes and anchored at the top by a split cone, mechanical anchor, or resin grout. The bolts are put up in a definite pattern. The idea is to clamp together the several roof beds to form a composite beam with a strength considerably greater than the sum of the individual beds acting separately. See also: slot-and-wedge bolt; pin timbering; rock bolting. CF: strata bolt.

roof control

The scientific study of the behavior of rock undermined by mining operations and the most effective measures of controlling movements and failure. The subject is comprehensive, including the systematic measurement of the movement of strata and the forces and stresses involved. An attempt is made to correlate data with rock types and the type of excavation. See also: rock mechanics.

roof cut

A machine cut made in the roof immediately above the seam. A roof cut is sometimes made in a soft band of dirt over the coal, which gives increased height in thin seams. The cut is made with a turret coal cutter.

roof cutting

It is a common occurrence to hear miners talk of gas cutting the roof and causing it to weaken; however, this condition is seldom encountered. There are some seams where gas does cut the roof, generally where top coal is left in gassy seams. The most common cause of roof cutting is its exposure to air. Gunite or painting of the top helps a condition of this kind.

roof drill

Various hydraulically operated mechanized machines designed to install roof bolts. Two workers can install up to 200 bolts per shift. Units are available in both standard and special design to satisfy requirements in different mines.


A roof that is tenacious and when allowed to fall breaks down in large blocks or frames of stone.


The wedging of a loaded wagon or horse against the top of an underground passage.

roofing hole

In West Wales, a small, steeply inclined stone drivage from a lower to an upper coal seam or for exploration in disturbed ground. Syn: roof-up.

roof jack

A screw- or pump-type extension post used as a temporary roof support.

roof layer

a. Uniformly thick layer of rock supported or clamped at the edges by pillars.

b. A layer of combustible gas under the roof of mine workings.

roof movement meter

See: romometer.

roof pendant

A downward projection of country rock into an igneous intrusion. CF: cupola. Syn: pendant.

roof pressure

The pressure that the overlying rocks exert on the support of mine workings. See also: ground pressure.

roof rock

Rock forming the ceiling of a cave passage, underground chamber, mine opening, etc.

roof shale

The layer or seam of shale occurring immediately above the Pittsburgh coal seam. Because of its friable nature, this shale or slate is taken down in most mining operations.

roof station

A survey station fixed in the roof of a mine roadway or working face.

roof stone

Scot. The stone immediately above a coal seam. See also: roof.

roof stringer

Used in a weak or scaly top in narrow rooms or entries that have short life. It is done by placing lagging bars running parallel with the working place above the header. It has limited uses because of necessary additional height and because its weight rests on the center of the header. See also: stringer.

roof testing

In the simple testing of the roof, it is struck by a hammer or a heavy object. A loose roof will give off a dull or hollow sound compared with a solid top, which has a clear ring. Good roof that has a clear ringing sound is called "bell top." Also known as sounding, sounding the roof, sounding the top, and jowling. Syn: top testing.

roof-testing tool

Usually a wooden pole with a metallic ball at the upper end.

roof-to-floor convergence

The deformation of the coal or ore pillars is estimated by monitoring the closure of the entry. This roof-to-floor convergence is generally measured with a tube extensometer, to an accuracy of 0.001 in (25.4 mu m), or a tape measure, to an accuracy of 0.01 ft (3.048 mm). Measurements are repeatedly taken as the mining geometry changes.


See: roofing hole.

roof work

A term applied to a vein worked overhead.


a. A place abutting an entry or airway where coal or ore has been mined and extending from the entry or airway to a face.

b. A wide working place in a flat mine corresponding to a stope in a steep vein. A chamber. CF: stope. c. A heading or short stall.


Said of a system of mining in which typically flat-lying beds of coal or ore are mined in rooms separated by pillars of undisturbed rock left for roof support. See also: bord-and-pillar working; County of Durham system. Syn: heading and stall.

room-and-pillar mining

In coal and metal mining, supporting the roof by pillars left at regular intervals.

room-and-pillar with waste filling

See: overhand stoping.

room boss

In bituminous coal mining, a miner who inspects the working face in working places (rooms) to determine whether mining operations are being carried on properly and safety regulations are being observed. Also called wall boss.

room conveyor

a. Any conveyor that carries coal from the face of a room toward the mouth. Normally, a room conveyor will deposit its coal into a car or another conveyor at the mouth of the room, but occasionally it will dump into a cross conveyor at some point between the face and the mouth.

b. See: underground mine conveyor.

room entry

Any entry or set of entries from which rooms are turned. A panel entry.

room neck

A short passageway from the mine entry to the room in which a miner works.

room system with caving

See: bord-and-pillar.


A monoclinic mineral, BiAsO (sub 4) ; monazite group; at Santiaguillo, Bolivia.

root clay

See: underclay.

root deposit

A lode or vein from which alluvial cassiterite or gold may have been derived.


a. A towed scarifier; sometimes used to break up a hard surface and prior to the use of bulldozers in removing overburden at quarries and opencast pits. A heavy-duty ripper.

b. A towed machine equipped with teeth, used primarily for loosening hard soil and soft rock.

root hook

A very heavy hook designed to catch and tear out big roots when it is dragged along the ground.

root-mean-square value

The root-mean-square value of an alternating current or voltage. It is the square root of the mean value of the squares of the instantaneous values taken over a complete cycle. When an alternating current or voltage is specified, it is almost invariably the root-mean-square value that is used. Also used of quantities that alternate over longer periods, for example, a month or year. Also known as effective value. Abbrev., R.M.S.

rope and button conveyor

A conveyor consisting of a rope with disks or buttons attached at intervals, the upper flight running in a trough. The coal or other material is dropped into the trough, and the conveyor either is actuated by the weight of the coal in the trough when the trough is inclined forming a retarding conveyor, or moves the coal along the trough where the gradient is insufficient or adverse. In the one case a brake is provided; in the other, the sprockets are actuated by a motor.

rope core

An important component of stranded ropes is the core, which may be either of fiber or of wire. In winding ropes it is generally made of manilla, sisal, or hemp. The function of the core is to support the strands and prevent them from bearing hard against one another. An even more important function is as a store for lubricant for the interior of the rope, and during manufacture it is saturated with lubricant.

rope cutter

See: hook tender.

rope diameter

The diameter of a steel wire rope is the maximum obtainable measurement across the outer edges of the strands. The size of fiber ropes is usually specified by their circumference. Modern steel wire winding ropes are large and heavy and may be 2-1/4 in (5.7 cm) in diameter for a moderately deep shaft.

rope driver

In bituminous coal mining, a foreperson who looks after the haulage cable and the equipment of trains of cars by which coal is hauled from the mine. The rope driver superintends the attaching of cars to cable by clipper and directs movement of the cable by signaling a slope engineer through a buzzer system.

rope driving

The transmission of power by means of rope gearing, as distinguished from belt drive.

rope drum

Any drum, powered or otherwise, on which rope is wound; e.g., mining machine rope drums, room hoist rope drums, etc.

rope fastening

The most suitable fastening between a wire rope and its socket is a white metal capping. Haulage ropes are generally doubled back on themselves around a steel thimble and secured with bulldog clips.

rope guide

Steel rope suspended in a vertical shaft to prevent excessive swinging of the cages or skips. Eight rope guides are generally used for the shaft, four for each cage, and two additional rubbing ropes are installed to prevent possible collision between the cages or skips. The ropes are suspended from girders fixed on the safety hook catch-plate platform and kept taut in the shaft by means of weights in the shaft bottom sump. The clearances between the cages, and also between the cage corners and the shaft wall, should be about 12 in (30.5 cm). See also: fixed guides.

rope haulage

a. Means of moving loaded and empty mine cars by use of wire rope; generally used on steep inclines where use of electric mine locomotives is inefficient.

b. Any transportation system employing a steel wire rope to haul the mine cars or trams. See also: direct-rope haulage; main-and-tail haulage; tail-rope haulage.

rope haulage systems

Systems of rope haulage may be classified as (1) self-acting or gravity planes; (2) engine planes; (3) tail-rope haulage; (4) endless-rope haulage; and (5) aerial tramways, which are frequently considered by themselves, since they are not applied to transporting material underground.

rope lay

That length of rope in which one strand makes one complete revolution about the core.

rope plucking

The sudden jerking or twitching of a haulage rope due to the rope laps slipping to a smaller diameter on the drum. A severe plucking of a rope may be felt faintly more than 800 yd (725 m) distance from the engine. See also: overhaul.

rope rider

An employee whose duty it is to see that cars are coupled properly, and to inspect ropes, chains, links, and all coupling equipment. A trip rider. See also: brakeman.

rope roof bolt

A steel wire rope, with wedge heads fixed to its ends, used instead of the normal steel rod in roof bolting. Also known as cable bolting. The rope has a diameter of about 7/8 in (2.2 cm) and a length from 15 to 20 ft (4.5 to 6 m).

rope socket

A drop forged-steel device, with a tapered hole, which can be fastened to the end of a wire cable or rope and to which a load may be attached. It may be either the open- or closed-end type.


a. A line or double line of suspended ropes, usually wire, along which articles of moderate weight may be transported on slings, either by gravity or power; much used in mining districts for transportation to watercourses or to railway lines. An aerial tramway.

b. See: aerial ropeway.

Ropp furnace

A long reverberatory furnace with a series of plows or rakes that are drawn over the hearth by a continuous cable, moving the ore steadily from the feed to the discharge end.


A tetragonal mineral, CuInS (sub 2) ; chalcopyrite group; at Charrier, Allier, France.


a. A monoclinic mineral, 4[(Cu,Zn) (sub 2) (CO (sub 3) )(OH) (sub 2) ] ; forms green to blue spherules in oxidized zones of zinc-copper-lead deposits.

b. The mineral group glaukosphaerite, kolwezite, mcguinnessite, nullaginite, rosasite, and zincrosasite.

Roeschen method

A combustible-gas drainage method utilizing controlled drainage from the coal seams as they are being mined. This method, which is also known as the pack cavity method, was devised to extract gas from the mined-out areas of advancing longwall mining systems by leaving corridors or cavities at regular intervals in the pack.


A monoclinic and triclinic mineral, Ca(Fe,Mn) (sub 2) Be (sub 3) (PO (sub 4) ) (sub 3) (OH) (sub 3) .2H (sub 2) O .


A monoclinic mineral, K(V,Al,Mg) (sub 2) (AlSi (sub 3) )O (sub 10) (OH) (sub 2) ; mica group; soft; a source of vanadium.

rose beryl

The morganite variety of beryl.

rose bit

A hardened steel or alloy noncore bit with a serrated face to cut or mill out bits, casing, or other metal objects lost in the hole. Also used to mill off the rose-bit dropper on a Hall-Rowe wedge. Also called mill; milling bit. CF: junk mill.

rose copper

See: rosette copper.

rose diagram

A circular diagram for plotting strikes (with or without dips) of planar features, such as joints, faults, and dikes; so named because clusters of preferred orientations resemble the petals of a rose.


a. A monoclinic mineral, Ca (sub 2) (Co,Mg)(AsO (sub 4) ) (sub 2) .2H (sub 2) O ; roselite group; forms a series with wendwilsonite; dimorphous with roselite-beta; perfect cleavage.

b. The mineral group brandtite, roselite, wendwilsonite, and zincrosasite.

rose of cracks

The system with radial cracks issuing from the center of the hole as a result of the tangential stresses.

rose opal

A variety of opaque common opal having a fine red color.

rose quartz

Crystalline quartz with a rose pink color, due probably to titanium in minute quantity. The color is destroyed by exposure to strong sunlight. Used as a gem or an ornamental stone. See also: Bohemian ruby.

rose steel

A steel that shows a peculiar fracture and texture in the interior, different from that near the surface.

rose topaz

The yellow-brown variety of topaz changed to rose pink by heating. These crystals often contain inclusions of liquid carbon dioxide.


A radially symmetric, sand-filled crystalline aggregate or cluster with a fancied resemblance to a rose; formed in sedimentary rocks by barite, marcasite, or pyrite. See also: petrified rose.

rosette copper

Disks of copper (red from the presence of suboxide) formed by cooling the surface of molten copper through sprinkling with water. Also called rose copper.

rosette texture

A flowerlike or scalloped pattern of a mineral aggregate.

rose vitriol

Cobalt sulfate. See also: bieberite. Also called cobalt vitriol; red vitriol.


A monoclinic mineral, S (gamma sulfur); dimorphous with sulfur. Syn: gamma sulfur.


a. The hard, amber-colored residue left after distilling off volatile oil from pine pitch.

b. To melt a resin and apply a coat to the right-handed threads of heated rod couplings; the coating sets when cooled, which permits the rods to be used in the same manner as left-hand-threaded rods in fishing operations. Also called rosining.

rosin blende

A yellow variety of zinc blende, ZnS. When dark in color it is called blackjack.

rosined joints

Drill-rod or casing couplings to which hot rosin was applied and that were joined before the rosin cooled.


The act or process of milling a metal object in a borehole with a rose bit.

rosin jack

A yellow variety of sphalerite. Also called resin jack, rosin blende, rosen zinc. CF: blackjack.

Rosin-Rammler equation

An equation relating to fine grinding: for most powders that have been prepared by grinding, the relationship between R, the residue remaining on any particular sieve, and the grain size in micrometers (x) is exponential: R = 100e (super -bx (super n) , where e is the base of the natural logarithm and b and n are constants.

rosin tin

A reddish or yellowish variety of cassiterite. Also spelled resin tin.

rosin zinc

Sphalerite of a rosiny appearance.


a. See: anorthite.

b. An impure muscovite as alteration product.

rosiwal analysis

In petrography, a quantitative method of estimating the volume percentages of the minerals in a rock. Thin sections of a rock are examined with a microscope fitted with a micrometer that is used to measure the linear intercepts of each mineral along a particular set of lines. This method is based on the assumption that the area of a mineral on an exposed surface is proportional to its volume in the rock mass.


A rose-pink variety of grossulatire garnet. Also called landerite and xalostocite. From Xalostoc, Morelos, Mexico.

Ross and Welter furnace

A multiple-deck roasting furnace of the annular type; used in Germany.

Ross feeder

Mechanism for control of rate of feed of coarse ore in the primary and secondary crushing system. Several heavy loops of chain lie above and bear on ore that rests in the delivery chute at just above its natural angle of repose. When the shaft from which the loops are suspended is rotated by its small motor, ore slides under control.

Rossie furnace

An American variety of hearth for the treatment of galena, differing from the Scotch hearth in using wood as fuel, working continuously, and having hollow walls, to heat the blast.

Rossi-Forel intensity scale

A scale for rating earthquake effects. Devised in 1878 by de Rossi (Italy) and Forel (Switzerland). No longer in general use, having been supplanted by Wood and Neumann's Modified Mercalli intensity scale of 1931.


A brown to garnet-red resinous material forming lenticular masses in the coal of Carusthia.


A tapered float rises or falls in a transparent tube in accordance with the velocity of the rising liquid. Variations include spinning floats and magnetic or radioactive ones for use with opaque fluids. Rate-of-flow indicator.


Laboratory screen shaker widely used in screen sizing analysis. Up to seven 8-in round screens are nested on the appliance and given a shaking, rotary, and tapping motion.


See: rotary table; rotary-drill rig.

rotary bit

As used in a broad sense by drillers, a roller bit.

rotary boring

A system of boring, using usually hollow rods, with or without the production of rock cores. Rock penetration is achieved by the rotation of the cutting tool. The method is used extensively in exploration, particularly when cores are required. It is the usual method in oil well boring with holes from 6 to 18 in (15 to 45 cm) in diameter. See also: boring; diamond drilling; rotary drill.

rotary breaker

A breaking machine for coal, rock, or minerals. It consists of a trommel screen with a heavy cast steel shell fitted internally with lifts that progressively raise and convey the coal and stone forward and break it. As the material is broken the undersize passes through the apertures, so that excessive degradation does not occur. See also: trommel; Bradford breaker.

rotary bucket drill

A rotary-type drill on which a rotary bucket is fastened to the kelly bar. The bucket is equipped with a hinged bottom, which has straight-edged cutting blades or teeth. When rotated by the kelly bar, the bucket loads from the bottom; when filled, it is withdrawn from the hole and dumped by unlatching the bottom. Holes 30 to 250 cm in diameter can be drilled with this machine in soft, boulder-free ground. Also called bucket rig; dry-hole digger; rathole rig. See also: bucket drill.

rotary compressor

A compressor designed for a delivery pressure of 100 psi (690 kPa) and ranging in capacity from 60 to 300 ft (super 3) /min (2.1 to 8.5 m (super 3) /min). See also: air-conditioning process.

rotary drier

A drier in the shape of an inclined rotating tube used to dry loose material as it rolls through.

rotary drill

Broadly, various types of drill machines that rotate a rigid, tubular string of rods to which is attached a bit for cutting rock to produce boreholes. The bit may be a roller cone bit, a toothed or fishtail drag bit, an auger bit, or a diamond bit. See also: core drill; rock drill. CF: diamond drill; shot drill.

rotary-drill cuttings

The chips and pulverized rock produced by the abrasive and chipping action of a drag, roller bit, or diamond bit when used on a diamond- or rotary-drill machine to drill a borehole. CF: cuttings.

rotary drilling

The hydraulic process of drilling that consists of rotating a column of drill pipe, to the bottom of which is attached a drilling bit, and during the operation, circulating down through the pipe a current of mud-laden fluid, under pressure, by means of special slush pumps. The drilling mud and cuttings from the bit are forced upward and outside the drill pipe to the surface. CF: cable-tool drilling.

rotary drill motor

The space available in the casing of a pneumatic rotary rock or coal drill is necessarily limited and precludes the use of a reciprocating engine. The power unit used instead is similar in design to the vane compressor. The rotor runs at a very high speed, between 3,500 rpm and 4,000 rpm, and this is reduced by gearing to give a drill spindle speed of about 650 rpm.

rotary-drill rig

A rotary drill complete with accessory tools and equipment necessary to drill boreholes.

rotary dump

An apparatus for overturning one or more mine cars simultaneously to discharge coal. They may rotate either 180 degrees or 360 degrees .

rotary dump car

A standard small car in which the car body, of about 2 yd (super 3) (1.5 m (super 3) ) capacity, is mounted on a turntable in the car frame. The car body may be swung by hand to dump over either side or either end.

rotary dumper

A steel structure that revolves a mine car and discharges the contents, usually sideways, into a bunker or onto a screen.

rotary excavator

Earth-moving machine with vertical wheel that carries digging buckets peripherally. These loosen soil and deliver to short conveyor loader, the assembly being mounted on crawler track. Capacity up to 5,000 st/h (4,500 t/h). Also called bucket wheel excavator.

rotary fault

See: rotational fault.

rotary feed table

a. A feeder comprising a horizontal rotating circular plate mounted under the mouth of a hopper and arranged with an adjustable plow to control the rate of flow of material over the edge of the plate.

b. See: disk feeder.

rotary furnace

Horizontally mounted cylinder rotating between trunnions through which gas or oil flame is introduced.

rotary-percussive drill

A drilling machine that operates as a purely rotary machine to which is added a percussive action. The specially designed rotary-percussive drilling bit not only gives a greater penetration rate, but is also able to operate longer without deterioration of the cutting edges. A disadvantage is the great size of the air-operated machine, which is usually mounted on a carriage.

rotary percussive drilling

A method of drilling in which repeated blows are applied to the bit, which is continually rotated under power.

rotary pump

A positive-displacement pump in which the liquid-propelling parts are cams, gears, impeller wheels, etc., rotating within a case, as distinguished from those pumps that move liquids by means of the to-and-fro motion of a piston within a cylinder. CF: centrifugal pump.

rotary screen

a. A screen for sizing aggregate and similar material; it is a pierced rectangular plate bent into a cylinder.

b. See: trommel.

rotary shot drill

a. Any rotary drill used to drill blastholes.

b. See: seismograph drill.

rotary smelter

Any of the cylindrical smelters that depend on slow rotation about a horizontal axis for agitation of the molten mass. See also: smelter.

rotary sorting table

A circular plate conveyor to effect a preliminary grading of coals and removal of stone by hand. A screened-out fraction of the run-of-mine coal is delivered to the table by chute from a conveyor. As the stream of coal revolves on the table, the various grades of coal and the dirt are raked into positions where they are diverted by plows into chutes. The operators are positioned on the inner and outer edges of the table and the coal is not handled but only raked. Syn: circular grading table.

rotary table

a. The geared rotating table that propels the kelly and the drill stem when drilling a borehole with an oilfield-type rotary rig. Also called rotary; table; turntable.

b. The mechanism used in some forms of rotary drilling to rotate the drilling column.

rotary vane feeder

A rotor of cylindrical outline with radial, spaced plates or vanes rotating on a horizontal axis, for controlling the flow of bulk materials.

rotary vibrating tippler

A tippler designed to overcome the tendency for coal or dirt to stick to the bottom of the tubs or mine cars. When the tippler is in the inverted position, the car rests upon a vibrating frame that gives it a high-speed vertical jolting motion, which frees any material tending to stick inside the car.

rotating casing screw conveyor

A screw conveyor in which the tubular casing rotates at a different speed or in an opposite direction to the conveyor screw. See also: screw conveyor.

rotational fault

A fault on which rotational movement is exhibited; a partial syn. of hinge fault. CF: hinge fault; scissor fault. Syn: rotary fault.

rotational flow

Turbulent flow involving all parts of a moving liquid.

rotational movement

Apparent fault-block displacement in which the blocks have rotated relative to one another, so that alignment of formerly parallel features is disturbed. CF: translational movement. See also: rotational fault.

rotational shear

One of four types of slope failure. Failure by rotational shear produces a movement of an almost undisturbed segment along a circular or spoon-shaped surface and occurs in comprehensive, uniform material. This material would not be affected by geological planes of weakness. Failure of this type can occur from causes that either increase the shear stresses or decrease the shear strength of the material.

rotational slide

A slide of homogeneous earth or clay in which the slip surface of failure closely follows the arc of a circle.

rotational transformation

An isochemical phase change involving only a shift in angle of chemical bonds, e.g., beta-quartz to alpha-quartz. CF: phase transformation; displacive transformation; reconstructive transformation; dilational transformation.

rotational wave

See: S wave.

rotation firing

Crushing a small piece of rock with a first explosion, and timing other holes to throw their burdens toward the space made by that and other preceding explosions. Also called row shooting.

rotation recorder

An instrument for measuring any slight rotation of a bridge support under load. See also: spread recorder.


See: rotche.


S. Staff. A soft and moderately friable sandstone. Also called roach; rotch; roche.


A brown variety of andradite garnet.

Rot I plate

See: gypsum plate; selenite plate.

rotobelt filter

Drum-type vacuum filter in which the membrane is a belt, which leaves the drum at discharge point and is returned via pulleys. This arrangement facilitates washing of filter cake from both sides, also discharge.

roto finish

A tumbling method using special chips and chemical compounds.


Any unit that does its work in a machine by spinning and does not drive other parts mechanically.

rotor steel process

A steelmaking process using the principle of rotation as in the Kaldo process. It has two lances; one above the bath surface uses low-pressure oxygen to burn carbon monoxide from the bath, while the other blows oxygen onto the bath at high pressure to obtain similar fast oxidation as in the L.D. steel process.

rotten reef

S. Afr. Decomposed, soft country rock found in connection with auriferous conglomerates.


A soft, light, earthy substance consisting of fine-grained silica resulting from the decomposition of siliceous shale-on limestone. It is used for polishing. CF: diatomite.


a. Highly fractured, broken, or cavey ground.

b. An uncut gemstone. Pertaining to an uncut or unpolished gemstone; e.g., a rough diamond.


Term used in the dimension stone industry for ends of blocks that are used as byproducts.

rough diamond

A diamond in its natural state.

rougher cell

Flotation cells in which the bulk of the gangue is removed from the ore or coal.

rough ground

Highly fractured, fragmented, or cavey rock formations.


Upgrading of run-of-mill feed either to produce a low-grade preliminary concentrate or to reject valueless tailings at an early stage. Performed by gravity on roughing tables, or in flotation in rougher circuit. See also: cleaning.

roughing hole

A hole to receive slag from a blast furnace, or molten iron when it is undesirable to let it run into pigs.

roughing mill

a. A metal disk charged with an abrasive, used for the first work in grinding gems.

b. A set of roughing rolls.

roughing rolls

The rolls of a train that first receive the pile, ingot, bloom, or billet, and partly form it into the final shape. Also called breaking-down or roughing-down rolls.

roughing tool

The ordinary tool used by machinists for removing the outer skin and generally for heavy cuts on cast iron, wrought iron, and steel.

rough stone

a. See: rough diamond.

b. A gemstone that has not yet been polished or cut.


Corn. A quarry term to designate a direction along which there is no natural cleavage in a rock. See also: cleaving way; quartering way.


a. A planned pattern of drill holes or series of shots intended to be fired either simultaneously or with delay periods between shots; also, the muck pile obtained when the round is blasted.

b. A round generally consists of cut holes, easers, and trimmers. See also: drill-hole pattern; shot firing in rounds. c. The holes drilled for blast, the advance from a blast, or the ore, or rock from a single blast. d. A blast including a succession of delay shots. e. In the operation of a blast furnace, one complete charge of ore, coke, and limestone.


See: circuits.

round-face bit

A bullnose bit; also, any bit the cutting face of which is rounded, such as a single- or double-round nose bit.

round-headed buttress dam

A mass concrete dam constructed of parallel buttresses thickened at the upstream end until they conjoin. See also: multiple-arch dam.

round hook

A hook that has a smooth inner surface and will slide along a chain.

rounding tool

A forming or swaging tool having a semicylindrical groove; a blacksmith's swage or collar tool.

round kiln

See: beehive kiln.


a. A rounded rock fragment of any size larger than a sand grain; a group name for pebbles, cobbles, or boulders -- any or all of these.

b. A diamond crystal with an arched facet. c. A term proposed by Fernald (1929) for any naturally rounded rock fragment of any size larger than a sand grain (diameter greater than 2 mm), such as a boulder, cobble, pebble, or granule. See also: cobblestone.

round strand rope

A rope composed of a number of strands, generally six in number, twisted together or laid to form the rope around a core of hemp, sisal, or manilla, or, in a wire-cored rope, around a central strand composed of individual wires.

round trip

The process of pulling the drill string from a borehole, performing an operation on the string (such as changing a bit, emptying the core barrel, etc.), and then rerunning the drill string into the borehole. See also: trip.


a. Corn. Coarse, undressed tin ore; refuse from stamping mills.

b. N. Staff. A seam or bed of coal. c. A line of points in a lattice. See: lattice.


An orthorhombic mineral, Ca (sub 2) Mn (sub 2) B (sub 4) O (sub 7) (OH) (sub 6) ; forms a series with fedorovskite; forms light brown laths; at Franklin, NJ.


An amorphous mineral, Y (sub 4) FeSi (sub 4) O (sub 14) F (sub 2) (?) ; massive; dark-green where fresh; becomes brick red on alteration.

row shooting

In a large blast, setting off the row of holes nearest the quarry face first, and other rows behind it in succession.


A nonpermitted gelatinous explosive; medium strength, high density, and good water resistance. Used in tunneling in nongassy mines in rocks of medium hardness.

royal barren

Solution overflowed from first ion-exchange column in a series that is receiving and stripping pregnant uranium liquor; contains some uranyl.


a. A lease by which the owner or lessor grants to the lessee the privilege of mining and operating the land in consideration of the payment of a certain stipulated royalty on the mineral produced.

b. See: overriding royalty. c. Ownership of mineral rights under restricted terms. d. Eng. The mineral estate or area of a colliery, or a portion of such property. A field of mining operations. e. The landowner's share of the value of minerals produced on a property. It is commonly a fractional share of the current market value (oil and gas) or a fixed amount per ton (mining). See also: take.


In foundry work, centrifugal belt thrower. Short length of conveyor belting travels at 2,000 to 4,000 ft/min (600 to 1,200 m/min) and conditions molding sands by discharging them vigorously so as to mix and partially dry them. Similar arrangement also used in forming storage piles and loading small material to ships.


a. A monoclinic mineral, FeSO (sub 4) .4H (sub 2) O .

b. The mineral group including aplowite, boyleite, ilesite, rozenite, and starkeyite.