CHAPTER 15 GLOSSARY OF GEOLOGICAL, MINERAL EXPLORATION AND MINING TERMS

• Jurisdiction: United States

Mining Exploration Technology for Lawyers and Landmen
(Apr 1980)
CHAPTER 15
GLOSSARY OF GEOLOGICAL, MINERAL EXPLORATION AND MINING TERMS
John C. Lacy
Institute Speakers

ADIT — A nearly horizontal passage from the surface by which a mine is entered and unwatered. In the U.S., an adit is usually called a tunnel, though the latter strictly speaking, passes entirely through a hill and is open at both ends — frequently called "drift" or "adit" level. (CMA)

AIR CIRCULATION — A large volume of air under compression used in lieu of a liquid as a medium to cool the bit and eject the cuttings from the bore hole. (Cumming & Wicklund)

AIR TRACK DRILL — A heavy drill mounted on crawler tracks that are controlled by separate air motors. (CMA)

ALLOY — A metal which is composed of two or more elements. In the process of alloying intentional additions are made to improve the properties. (CMA)

ALLUVIAL — Deposited by a stream. (CMA)

ALTERATION — Change in the mineralogical composition of a rock typically brought about by the action of hydrothermal solutions. (CMA)

AMENABILITY — Characteristic reaction of minerals to basic methods of mineral processing. (CMA)

ANEMOMETER — An instrument for measuring the velocity of air currents; specifically, in mines, a common form consists of a small delicately-mounted disk fan connected by means of gears with indicating dials; especially useful when air current is over 100 fpm. (CMA)

ANGSTROM UNIT — One angstrom (O_A) is equal to one ten millionth of a millimeter or .000 000 00393 inch. (CMA)

ANION — An ion carrying a negative charge. (CMA)

ANISOTROPIC — Exhibiting different properties when tested along axes in different directions. (Cumming & Wicklund)

ANNULAR SPACE — The space between two concentric pipes, or the casing and the wall of the hole, or between drill pipe and casing. (Cumming & Wicklund)

ANODE — The electrode which gives off positive ions, or toward which negative ions collect. (CMA)

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ANTICLINE — See fold. CMA)

APEX — In United States mining law used to designate the highest elevation of a vein. (BM) The top or terminal edge of a vein as it makes its closest approach to the surface of the ground. It is not (repeat, NOT) the highest point along a vein. It is a line which may be a part of the outcrop of a vein (since a vein had width, the apex line is the center-line of a vertical vein and the higher or leading edge of a vein inclined from the vertical) and exists even where the vein does not outcrop (in which case it is called a blind apex). (Sherwood)

APLITE — A dike rock composed almost entirely of light-colored minerals and having a characteristic fine-grained granitic (aplitic) texture. (Wray)

AQUIFER — Water-bearing layer or formation. (CMA)

ASSAY — To determine the amount of metal contained in an ore. (CMA)

ATTITUDE — Direction and degree of dip of a structural plane (bed, vein, fault). (CMA)

BACK FILL — The rough material used to fill in again a place from which the earth has been removed. (CMA)

BASALT — A fine-grained basic rock usually occurring in volcanic flows, dikes and sills. An extrusive igneous rock containing about 49 percent SiO₂ and composed primarily of calcic plagioclase and pyroxine, with or without olivine. (CMA and Wray)

BATHOLITH — A very large mass of intrusive rock which in most cases cuts across the invaded rocks. (CMA)

BED — Layer in body of sedimentary rock stratum. (CMA)

BEDROCK — General term for the rock, usually solid, that underlies soil or other uncnsolidated, superficial material. (Cumming & Wicklund)

BENEFICIATION — Treatment of crude ore to improve its quality for some specific purpose. (CMA)

BIT CORING — An annular metal shell threaded to the end of a string of drill rods and set with diamonds, producing a cylindrical rock core and cuttings. (Cumming & Wicklund)

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BIT IMPREGNATED — Sintered matrix drill bit incorporating fragmented bortz of selected screen sizes and small whole diamonds. When worn out the diamonds are not always salvaged. (Cumming & Wicklund)

BIT ROLLER — Various styles for drilling large holes (4 1/4" to 17 1/2") in soft to hard formations, such as limestones, shales, granites, etc. Usually non-coring and not diamond set. (Cumming & Wicklund)

BLANKET VEIN — A loose term applied to horizontal mineralized zones; technically, a layer of sedimentary rock, such as limestone, which has been mineralized. Distinguished from an intrusive formation inserted between pre-existing strata or horizontally across pre-existing rock, such as a mineralized sill, although such a deposit is within the possible definitions of vein. (Sherwood)

BOULDER — A fragment of rock transported by natural means from a distance. Usually large and rounded. The agent of movement and attrition may be a glacier, stream or beach. (Cumming & Wicklund)

BOULDER CLAY — The stiff, hard and usually unstratified clay of glacial origin with boulders scattered through it. Also called till, tillite, hardpan, drift. (Cumming & Wicklund)

BRECCIA — rock consisting of fragments, more or less angular in a matrix of finer-grained material or of cementing material. (CMA)

BRECCIA PIPE — A cylindrically shaped and vertical or steeply dipping geologic feature composed of fragments in a matrix; may or may not contain ore materials. (Peters)

BULK FLOTATION — The raising as a mineralized froth of more than one mineral in one operation. (CMA)

CFM — Cubic Feet per Minute (Cumming & Wicklund)

CABLE TOOL DRILL — A drill used largely in placer sampling and in drilling water wells. It is operated by a cable raising and dropping a long, heavy chisel bit tool. (Cumming & Wicklund)

CAPPING — The leached and limonite (iron oxide) stained upper portion of disseminated sulfide orebodies, especially porphyry copper deposits; a term used in place of gossan when referring to porphyry copper deposits. (Peters)

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CASING — Special pipe in which drill rods rotate and used either to hold back overburden or to line defective cavernous drill holes. Usually made from seamless tubing. (Cumming & Wicklund)

CAVING — The controlled, gravity or mechanically induced fracturing of a mineralized area for the production of ore. (CMA)

CHUTE/ORE PASS — Vertical or inclined passageway for downward movement of ore. (CMA)

CLASSIFICATION — Sorting of particles in accordance with their rate of fall through a fluid. (CMA)

CLEAVAGE PLANE — A crystallographic lattice plane on which fracture may occur. (CMA)

COMMINUTION — Crushing and/or grinding of ore by impact and abrasion. Usually, the word "crushing" is used for dry methods and grinding for wet methods. Also, crushing usually denotes reducing the size of course rock while grinding usualy refers to the reduction of fine sizes; less than 1/2" — example. (CMA)

CONCENTRATE — The valuable mineral separated from ore undergoing a specific treatment. (CMA)

CONGLOMERATE — A cemented clastic rock containing rounded fragments of gravel of pebble size. (CMA)

CONTACT — Bounding surface between two rock units. (CMA)

CONTACT-METASOMATIC DEPOSIT — A mineral deposit formed by high-temperature magmatic emanations along an intrusive igneous contact. (Wray)

CORDILLERA — A whole mountain province, including all the subordinate mountain ranges and groups and the interior plateaus and basins, forming a mountain system of great linear extent. (Wray)

CORE — The rock cylinder produced by the hollow, coring diamond bit. (Cumming & Wicklund)

CORE BARREL — Above the bit is a reaming shell and a length of tubing usually 10 feet long, to hold the core until raised to surface. These barrels are of single or double or triple tubing, and of swivel or rigid type. (Cumming & Wicklund)

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CORE LIFTER — A tapered split ring inside the bit and surrounding the core. On lifting the rods, the taper causes the ring to contract in diameter, seizing and holding the core. Also called core spring or core catcher. (Cumming & Wicklund)

COUNTRY ROCK — The rock (usually worthless) surrounding a vein and forming its walls, although the boundaries between the two may be economic rather than geological. Where the attitude of a vein is anything other than perpendicular, the country rock above the vein is called the hanging wall (rock falls from the hanging wall) and that below the vein is called the foot wall (the miner stands on the foot wall). (Sherwood)

CROSSCUT — A horizontal opening driven across the direction of the main workings; a connection between two drifts, tunnels, or levels. (CMA)

CRYSTAL — Atoms in a crystal are arrayed in an orderly pattern that repeates itself in three dimensions throughout the interior of the crystal. (CMA)

CRYSTALLOGRAPHY — Science of the shapes, color, chemical, electrical, physical and optical properties of crystals. (CMA)

DENSITY — Concentration of matter, measured by mass per unit volume, often expressed as grams per cubic centimeter, pounds per gallon, or pounds per cubic foot. (Cumming & Wicklund)

DEPRESSING AGENT — One used in flotation process to render selected mineral(s) more hydrophilic or to prevent collector action, thus helping to keep them from reporting with the mineralized froth. (CMA)

DEVELOPMENT WORK — Work undertaken in order to open up orebodies as distinguished from the work of actual ore extraction. (CMA)

DEVIATION — DEFLECTION — The tendency of a drill hole to change from its intended course either intentionally or from various causes in the hole or the equipment. (Cumming & Wicklund)

DIAMOND DRILL — A rotary drilling device using a bit set with diamond as the rock cutting tool — usually used to recover the rock core through the hollow drill stem. (CMA)

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DIFFERENTIAL FLOTATION — Concentration as separate products of a series of minerals removed from an ore by froth flotation. (CMA)

DIFFUSION — A process of self-mixing of atoms, generally from areas of higher to areas of lower concentrations of the constituents. (CMA)

DIKE — A discordant tabular body...