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Glossary Agglomerate: reform into lumps of suitable size (Encyclopedia Britannica, 2022b) Base metal: a metal (e.g., zinc, lead) of comparatively low value compared to precious metals (e.g., gold, silver) (Merriam-Webster, 2022) Breccia: sharp-angled fragmented rock (Merriam-Webster, 2022) Cambrian: a geologic period that began approximately 542 million years ago and ended 488 million years ago (USGS, 2007a) Commercial gold mining: higher-tech gold mining that occurs on a larger scale than small-scale gold mining Comminution: the crushing and grinding of a material/ore to reduce it to smaller or finer particles (Multotec Group, 2019) Criteria air pollutants: particulate matter, photochemical oxidants (including ozone), carbon monoxide, sulfur oxides, nitrogen oxides, and lead (EPA, 2022c) Dip: the angle of inclination measured from horizontal of a planar geologic feature (Encyclopedia Britannica, 2022b) Doré: recovered metal containing gold and silver (Encyclopedia Britannica, 2022b) En echelon: parallel or subparallel, closely spaced, steplike minor structural features in rock (Davis et al., 2011) Epithermal: deposited under conditions in the lower ranges of temperature and pressure (Merriam-Webster, 2022) Fugitive dust: small particles emitted to the air from open air sources or opening that are not a stack, chimney, or vent. Fugitive dust may include particulate material of a range of sizes, including PM10 (generally 10 microns in diameter or smaller) and PM2.5 (generally 2.5 microns in diameter or smaller) (9VAC5-50-70) Gabions: rectangular baskets filled with stone or dirt for support (Merriam-Webster, 2022) Gangue: the economically worthless material that surrounds, or is closely mixed with, a desirable mineral in an ore deposit (Mindat, 2022a) Geosynthetic: a planar product made from polymeric material used with soil, rock, or earth for construction (Idaho Transportation Department, 2011) Geotextiles: a permeable geosynthetic comprised solely of textiles (Idaho Transportation Department, 2011) Greenschist-facies: low to medium metamorphism corresponding to temperatures of about 300°C to 500°C and pressures of 3 to 20 kbar, which is typical of continental collision tectonics (Arndt, 2011) Hydrometallurgy: the treatment of ores by wet processes such as leaching (Merriam-Webster, 2022) Igneous rock: rock formed by magma or lava (Merriam-Webster, 2022) Indicated mineral resource: that part of a mineral resource for which quantity and grade or quality are estimated on the basis of adequate geological evidence and sampling (17 CFR § 229.1300) 187
188 THE POTENTIAL IMPACTS OF GOLD MINING IN VIRGINIA Intrusive: igneous rock formed within the crust Island arc: a curved chain of volcanic islands that are found along tectonic plate margins (Merriam-Webster, 2022) Lixiviant: a liquid medium used in hydrometallurgy to selectively extract the desired metal from the ore or mineral (AIME, 1917) Lode: an ore body found within rock (Encyclopedia Britannica, 2022b) Mafic: a rock rich in magnesium and iron and relatively depleted in silica (Merriam-Webster, 2022) Measured mineral resource: that part of a mineral resource for which quantity and grade or quality are estimated on the basis of conclusive geological evidence and sampling (17 CFR § 229.1300) Mesozoic: a geologic era that began 251 million years ago and ended 66 million years ago (USGS, 2007a) Metaclastics: metamorphosed clastic sedimentary rocks, which is composed of detrital rock and mineral fragments (Mindat, 2022b) Metalloid: an element with properties that are intermediate between those of metals and nonmetals (Merriam- Webster, 2022) Metamorphic rock: formed under extreme heat and temperature (Merriam-Webster, 2022) Metasedimentary rocks: sedimentary rocks that have been metamorphosed Mineral: a crystalline inorganic substance (Merriam-Webster, 2022) Ordovician: a geologic period started 488 million years ago and ended 444 million years ago (USGS, 2007a) Ore: a naturally occurring accumulation of one or more valuable mineral resources (Merriam-Webster, 2022) Orogenic gold deposits: Deposits that are formed from the remobilization of gold scavenged during metamorphism and redeposited elsewhere (Sillitoe, 2020) Paleozoic: a geologic era that began 542 billion years ago and ended 251 million years ago (USGS, 2007a) Placer: deposit that has been moved following river, marine, or glacial action (Merriam-Webster, 2022) Plutonic: igneous rock formed deep underground Precambrian: a geologic period that began approximately 4,600 million years ago and ended 542 million years ago (USGS, 2007a) Processing: in this report, processing indicates both the physical processing sometimes called âbeneficiationâ along with chemical processing that is principally hydrometallurgical for gold, although the last steps are pyrometallurgical Proterozoic: a geologic eon that began approximately 2.5 billion years ago and ended 542 million years ago (USGS, 2007a) Pulp: is a freely flowing mixture of powdered ore and water (911 Metallurgist, 2016) Pyrometallurgy: chemical metallurgy depending on heat action (such as roasting and smelting) (Merriam- Webster, 2022) Recreational gold mining: mining, often by a few individuals, primarily for recreation. This is often limited to panning for alluvial gold in streams Sedimentary rock: formed from sediment deposited by water or air (Merriam-Webster, 2022) Shotcrete: pneumatically applied concrete consisting of cement, aggregates, water, and additives such as accelerators, silica fume, and steel fibers (USACE, 1993) Slag: the material that is left when rocks that contain metal are heated to get the metal out (Encyclopedia Britannica, 2022b) Small-scale mining: low-tech, labor-intensive mineral extraction and processing carried out mostly by local people (Hilson and Maconachie, 2020) Stopes: excavation areas underground that are formed as the ore is mined in successive layers (Merriam- Webster, 2022) Strike: the orientation of an imaginary horizontal line across the plan of a geologic feature (Encyclopedia Britannica, 2022b) Surfactant: a surface-active substance that lowers the surface tension (or interfacial tension) (Merriam- Webster, 2022) Tailings: the remaining waste following ore processing (Merriam-Webster, 2022)
GLOSSARY 189 Terranes: coherent units of Earthâs crust that have a distinct geologic history and that are bounded by faults (Encyclopedia Britannica, 2022b) Triassic: a geologic period that began approximately 251 million years ago and ended 200 million years ago (USGS, 2007a) Volcanic: igneous rock formed near the surface (Merriam-Webster, 2022) Volcanogenic massive sulfide: accumulations of sulfide minerals that form due to hydrothermal action on the seafloor; ancient varieties may now be exposed on land (Jamieson et al., 2016) Waste rock: bedrock that has been mined and transported out of the pit but does not have gold concentrations of economic interest
