Fissionable isotope
Isotope that can split apart when hit by a neutron at the right speed and thus undergo nuclear fission. Examples are uranium-235 and plutonium-239. See nuclear fission.
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Chapter 15 - Geologic Resources: Nonrenewable Mineral and Energy Resources
Exhaustible resource
See nonrenewable resource.
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Economic depletion
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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dredging
Type of surface mining in which chain buckets and draglines scrape up sand, gravel, and other surface deposits covered with water. It is also used to remove sediment from streams and harbors to maintain shipping channels. See dredge spoils. Compare area strip mining, contour strip mining, mountaintop removal, open-pit mining, subsurface.
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deuterium (D; hydrogen-2)
Isotope of the element hydrogen, with a nucleus containing one proton and one neutron and a mass number of 2.
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depletion time
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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crude oil
Gooey liquid consisting mostly of hydrocarbon compounds and small amounts of compounds containing oxygen, sulfur, and nitrogen. Extracted from underground accumulations, it is sent to oil refineries, where it is converted to heating oil, diesel fuel, gasoline, tar, and other materials.
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core
Inner zone of the earth. It consists of a solid inner core and a liquid outer core. Compare crust, mantle.
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contour strip mining
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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coal liquefaction
Conversion of solid coal to a liquid hydrocarbon fuel such as synthetic gasoline or methanol.
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