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| Form of aquaculture in which fish are cultivated in a controlled pond or other environment and harvested when they reach the desired size. See also fish ranching. |
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| Form of aquaculture in which members of a fish species such as salmon are held in captivity for the first few years of their lives, released, and then harvested as adults when they return from the ocean to their freshwater birthplace to spawn. See also fish farming. |
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| Concentrations of particular aquatic species suitable for commercial harvesting in a given ocean area or inland body of water. |
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| depletion of the pop,. of a wild species used as a resource to a level at which it is no longer profitable to harvest the species. |
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| catching fish in huge nets that drift in the water |
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| harvesting so many fish of a species, esp. immature fish, that not enough breeding stock is left to replenish the species and it becomes unprofitable to harvest them |
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| Type of surface mining used where the terrain is flat. An earthmover strips away the overburden, and a power shovel digs a cut to remove the mineral deposit. After removal of the mineral, the trench is filled with overburden, and a new cut is made parallel to the previous one. The process is repeated over the entire site. |
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| Form of surface mining used on hilly or mountainous terrain. A power shovel cuts a series of terraces into the side of a hill. An earthmover removes the overburden, and a power shovel extracts the coal, with the overburden from each new terrace dumped onto the one below. Compare area strip mining, dredging, mountaintop removal, open-pit mining, subsurface mining. |
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| The time it takes to use a certain fraction, usually 80%, of the known or estimated supply of a nonrenewable resource at an assumed rate of use. Finding and extracting the remaining 20% usually costs more than it is worth. |
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Term
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Definition
| Exhaustion of 80% of the estimated supply of a nonrenewable resource. Finding, extracting, and processing the remaining 20% usually costs more than it is worth. May also apply to the depletion of a renewable resource, such as a fish or tree species. |
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| Ore that contains a smaller amount of the desired mineral. |
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| Any naturally occurring inorganic substance found in the earth's crust as a crystalline solid. See mineral resource. |
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| Concentration of naturally occurring solid, liquid, or gaseous material in or on the earth's crust in a form and amount such that extracting and converting it into useful materials or items is currently or potentially profitable. Mineral resources are classified as metallic (such as iron and tin ores) or nonmetallic (such as fossil fuels, sand, and salt). |
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| Type of surface mining that uses explosives, massive shovels, and even larger machinery called draglines to remove the top of a mountain to expose seams of coal underneath a mountain. Compare area strip mining, contour strip mining. |
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| Using atoms and molecules to build materials from the bottom up using the elements in the periodic table as its raw materials. |
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| Removing minerals such as gravel, sand, and metal ores by digging them out of the earth's surface and leaving an open pit. Compare area strip mining, contour strip mining, dredging, mountaintop removal, subsurface mining. |
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Definition
| Part of a metal-yielding material that can be economically and legally extracted at a given time. An ore typically contains two parts: the ore mineral, which contains the desired metal, and waste mineral material (gangue). |
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| Layer of soil and rock overlying a mineral deposit. Surface mining removes this layer. |
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| Resources that have been identified and from which a usable mineral can be extracted profitably at present prices with current mining technology. See identified resources, undiscovered resources. |
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| Process in which a desired metal is separated from the other elements in an ore mineral. |
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| Unwanted rock and other waste materials produced when a material is removed from the earth's surface or subsurface by mining, dredging, quarrying, and excavation. |
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Definition
| Form of surface mining in which bulldozers, power shovels, or stripping wheels remove large chunks of the earth's surface in strips. See area strip mining, contour strip mining, surface mining. Compare subsurface mining. |
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Definition
| Extraction of a metal ore or fuel resource such as coal from a deep underground deposit. Compare surface mining. |
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Definition
| Removing soil, subsoil, and other strata and then extracting a mineral deposit found fairly close to the earth's surface. See area strip mining, contour strip mining, dredging, mountaintop removal, open-pit mining. Compare subsurface mining. |
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Definition
| Potential supplies of a particular mineral resource, believed to exist because of geologic knowledge and theory, although specific locations, quality, and amounts are unknown. Compare identified resources, reserves. |
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