This glossary is provided as a tool for studying
this chapter. Keep it handy while you read, in order to find definitions
of unfamiliar words, or of familiar words that may have an unfamiliar meaning
in the context of this chapter.
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Clean Air Act: The name given to a series of air-quality improvement
laws and their amendments passed in the United States beginning in 1963.
Critical mineral: A mineral necessary for defense of the United
States and available partly in America or partly from friendly nations.
Hydrothermal mineralization: A process of concentration of metallic
ores caused by high-temperature geochemical processes in underground waters.
Law of the Sea Treaty: A treaty establishing jurisdiction over marine
resources in coastal and deep-sea areas.
Placer deposit: A deposit of a mineral formed by a concentration
of heavy minerals in flowing water, such as by a stream or waves.
Recycling: Reprocessing of a used product for reuse in a similar
or different form.
Reserve: In the context of mineral resources, a deposit of known
location and quality that is economically extractable at the present time.
Stockpiling: Amassing amounts of some substance well beyond present
needs in anticipation of a shortage of that substance.
Strategic mineral: A mineral necessary for defense purposes for
which the United States is totally dependent on foreign sources.
Subeconomic resource: A resource that at present is unavailable
for use because of the high cost of extraction.
Substitutability: The degree to which one material can be substituted
for another in end uses.
Tailings: Solid waste products derived from mineral extraction or
Unidentified resource: A mineral resource assumed to be present
within known geologic districts, but not yet specifically located or characterized
Weathering: The breakdown of rocks into smaller particles or new
chemical substances as a result of exposure to water and air at the earth's