Mining Glossary R

Radioactivity - The property of spontaneously emitting alpha, beta or gamma rays by the decay of the nuclei of atoms.

Radon survey - A geochemical survey technique which detects traces of radon gas, a product of radioactivity.

Raise - A vertical or inclined underground working that has been excavated from the bottom upward.

Rake - The trend of an orebody measured along the direction of its strike.

Rare earth elements - Relatively scarce minerals such as niobium and yttrium.

Reaming shell - A component of a string of rods used in diamond drilling, it is set with diamonds and placed between the bit and the core barrel to maintain the gauge (or diameter) of the hole.

Reclamation - The restoration of a site after mining or exploration activity is completed.

Reconnaissance - A preliminary survey of ground.

Record date - The date by which a shareholder must be registered on the books of a company in order to receive a declared dividend or to vote on company affairs.

Recovery - The percentage of valuable metal in the ore that is recovered by metallurgical treatment.

Refractory ore - Ore that resists the action of chemical reagents in the normal treatment processes and which may require pressure leaching or other means to effect the full recovery of the valuable minerals.

Regional metamorphism - Metatnorphism caused by both the heat of igneous processes and tectonic pressure.

Replacement ore - Ore formed by a process during which certain minerals have passed into solution and have been carried away, while valuable minerals from the solution have been deposited in the place of those removed.

Reserve - That part of a mineral resource that can be mined profitably.

Resistivity survey- A geophysical technique used to measure the resistance of a rock formation to an electric current.

Resource - The calculated amount of material in a mineral deposit, clas-sified as measured, indicated, or inferred, based on the density of drill hole information used.

Resuing - A method of stoping in narrow-vein deposits whereby the wallrock on one side of the vein is blasted first and then the ore.

Reverberatory furnace - A long, fíat furnace used to slag gangue minerals and produce a matte.

Rhyolite - A fine-grained, extrusive igneous rock which has the same chemical composition as granite.

Rib samples - Ore taken from rib pillars in a mine to determine metal content.

Rights - In finance, a certified right to purchase treasury shares in stated quantities, prices and time limits; usually negotiable at a price which is related to the prices of the issue represented; also referred to as warrants. Rights and warrants can be bought and sold prior to their expiratory date because not all share-holders wish to exercise their rights.

Rock - Any natural combination of minerals; part of the earth's crust.

Rockbolting - The act of supporting openings in rock with steel bolts anchored in boles drilled especially for this purpose.

Rockburst - A violent release of energy resulting in the sudden failure of walls or pillars in a mine, caused by the weight or pressure of the surrounding rocks.

Rock factor - The number of cubic metres of a particular rock type required to make up one tonne of the material. One tonne of a highly siliceous ore may occupy 0.40 cubic metres, while a tonne of dense sulphide ore may occupy only 0.25 cubic metres.

Rock mechanics - The study of the mechanical properties of rocks, which includes stress conditions around mine openings and the ability of rocks and underground structures to withstand these stresses.

Rod mill - A rotating steel cylinder that uses steel rods as a means of grinding ore.

Room-and-pillar mining - A method of mining flat-lying ore deposits in which the mined-out area, or rooms, are separated by pillars of approximately the same size.

Rotary drill - A machine that drills holes by rotating a rigid, tubular string of drill rods to which is attached a bit. Commonly used for drilling large-diameter blastholes in open-pit mines.

Royalty - An amount of money paid at regular intervals by the lessee or operator of an exploration or mining property to the owner of the ground. Generally based on a certain amount per tonne or a percentage of the total production or profits. Also, the fee paid for the right to use a patented process.

Run-of-mine - A term used loosely to describe ore of average grade.