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candidate species - (3) species not protected under the Endangered Species Act but under consideration by the US Fish and Wildlife Service for inclusion on the list of federally threatened or endangered species.

canopy - (3) the uppermost layer consisting of the crowns of trees or shrubs in a forest or woodland.

carbonate - (4) a compound or mineral containing CO3 ion. Common carbonate minerals are the hexagonal carbonates calcite (CaCO3), dolomite [CaMg(CO3)2], magnesite (MgCO3), ankerite [Ca(MgFe)(CO3)2], siderite (FeCO3), rhodocrosite (MnCO3), and smithsonite (ZnCO3) and the basic carbonates malachite [CuCO3Cu(OH)2] and azurite [2CuCO3Cu(OH)2]. Carbonate minerals are important in ARD neutralization.

Carlin Trend - (3) an area 25 miles west of Elko in northeast Nevada that has become the most productive gold district in the United States. In this 5-by-40-mile area, gold production over the last several years has exceeded over 4 million ounces a year.

carrying capacity - (3) the maximum (animal) stocking rate possible without damaging vegetation or related resources. Carrying capacity may vary from year to year in the same area due to fluctuating forage production.

CECRA - (2) The State of Montana Comprehensive Environmental Cleanup and Responsibility Act.

CERCLA - (2) The Comprehensive Environmental Response, Compensation, and Liability Act of 1980, also known as Superfund. Amended in 1986 by the Superfund Amendments and Reauthorization Act (SARA). This federal statute is administered by the EPA.

channel - (3) a natural or artificial watercourse with a definite bed and banks to confine and conduct contiuously or periodically flowing water.

chemical equilibrium - (4) a chemical condition in which the rates of forward and reverse reactions are equal and the concentrations of reactants and products do not change with time. One of two major chemical conditions affecting drainage chemistry.

chlorosis - (3) the condition of plants when chlorophyll fails to develop and plants are yellowish white to white and poorly developed.

chronic toxicity - (4) a reduction in growth, reproduction and/or development, or the mutation of an exposed organism over a length of time. See also acute toxicity.

clay-sized - (4) particles < 2µm in diameter.

climax vegetation - (3) the final vegetation community and highest ecological development of a plant community that emerges after a series of successive vegetational stages. The climax community perpetuates itself indefinitely unless disturbed by outside forces.

coarse fragment - (4) particles > 2 mm in diameter.

colluvial - (3)(a) processes related to the slow movement of the ground due to gravity (creep); (b) a hillside deposit developed by mass movement of rock on slopes leading away from the exposed source rock (lode).

colluvium - (3) rock and soil accumulated at the foot of a slope from gravitational forces. (4) materials that reached their present positions as a result of direct gravity-induced movement involving no agent of transportation such as water or ice, although the moving material may have contained water or ice. Generally consist of massive to moderately well-stratified, non-sorted to poorly-sorted sediments with any range of particle sizes from clay to boulders and blocks. The character of a colluvial deposit depends on the nature of the material from which it was derived and the specific process whereby it was deposited.

comminution - (2) to reduce solids to minute particles by crushing and grinding to liberate metals.

community - (3) an assemblage of plant and animal populations in a common spatial arrangement.

compaction - (4) a process resulting in a reduction in volume. The change typically results from externally applied loads, creating tighter packing of the solid particles. In fine soils in particular, this requires an egress of pore water. Greater compaction often result in consolidation.

competent rock - (3) rock that, because of its physical and geolgical character, can sustain openings without any structural support except pillars and walls left during mining.

composite sample - (4) a sample created by combining different fractions (subsamples). Subsamples can be collected at different times or from different locations.

concentrate - (2) to separate metal or ore from the associated "gangue" (the worthless rock or vein matter in which valuable metals or minerals occur) or barren rock.

concentrator - (2) mill or plant in which ore is concentrated by removing unwanted constituents.

cone of depression - (3) a change (depression) in the water table surface at the site of an active well, resulting from the withdrawal of water.

consumers - (3) organisms, chiefly animals, that ingest other organisms or particulate organic matter.

contaminant - (4) introduced material which was either not previously present or was present in lesser amounts. The introduction of contaminants may make something toxic or otherwise unfit for use. Below certain amounts contaminant species (for example, nutrients) may be desirable constituents. Synonymous with the term pollutant.

cool-season plants - (3) plants whose major growth occurs during the late fall, winter and early spring. See also warm season plants.

core - (4) the long, cylindrical piece of rock, about 5-10 cm or more in diameter, removed by diamond drilling.

country rock - (1) a loose term to describe the general mass of rock adjacent to an ore body, as distinguished from the vein or ore deposit itself, (2) general term applied to the rock surrounding and penetrated by mineralized veins; in a wider sense applied to the rocks invaded by and surrounding and igneous intrusion, (4) a term applied to rocks intruded by an igneous intrusion or surrounding a mineral deposit.

crib - (1) a square, stacked, pillar-like framework of wooden or metal bars, filled with rock, used for support or strengthening.

cribbing - (1) timber framing to retain the walls and ceiling of an adit opening or drift, and prevent loose materials from falling, (2) a method of timbering in underground mining used primarily to rectify the removal of too great a percentage of the rock on the advance, and has the effect of replacing part of the rock.

crosscut - (2) (a) an underground mine passageway driven at right angles to the main entry to connect it with a parallel entry of air course, (b) a horizontal opening driven across the course of a vein or in general perpendicular to the direction of the main workings.

crusher - (2) a machine for crushing rock or other materials. Among the various types of crushers are the ball-mill, gyratory crusher, Hadsel mill, jaw crusher, rod mill, rolls, stamp mill, and tube mill.

cultural resource - (3) the fragile and nonrenewable remains of human activity that are found in historic districts, sites, buildings, and artifacts and that are important in past and present human events.

cut-off grade - (4) the lowest grade of mineralized material in a given deposit that qualifies as ore. Used in the calculation of ore reserves.

cyanide - (2) a salt or ester (compound formed by the reaction of an acid and an alcohol) of hydrocyanic acid. In aqueous solution, cyanide is used to dissolve metal from gangue material for later recovery; typically used for extracting gold or silver from ore.

cyanidation - (4) a method of extracting exposed gold or silver grains from crushed or ground ore by dissolving it in a weak solution of sodium- or calcium-cyanide. Also known as cyanide leaching. May be carried out in tanks inside a mill or in heaps of ore outdoors.

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