- alluvial placer
- 冲积砂矿床
English-Chinese geology dictionary (英汉地质大词典). 2013.
alluvial placer
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Placer deposit — In geology, a placer deposit or placer is an accumulation of valuable minerals formed by deposition of dense mineral phases in a trap site. The name is from the Spanish word placer , meaning alluvial sand . Types of placer deposits include… … Wikipedia
Placer mining — (pronounced plass er ) refers to the mining of alluvial deposits for minerals. This may be done by open pit (also called open cast mining) or by various forms of tunneling into ancient riverbeds. Excavation may be accomplished using water… … Wikipedia
placer mining — ☆ placer mining [plas′ər ] n. mining of placer deposits by washing, dredging, or other hydraulic methods * * * Oldest method of recovering gold from alluvial deposits. It takes advantage of gold s high density, which causes it to sink more… … Universalium
Alluvial fan — An alluvial fan is a fan shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a… … Wikipedia
alluvial deposit — noun clay or silt or gravel carried by rushing streams and deposited where the stream slows down • Syn: ↑alluvial sediment, ↑alluvium, ↑alluvion • Derivationally related forms: ↑alluvial (for: ↑alluvium) … Useful english dictionary
alluvial sediment — noun clay or silt or gravel carried by rushing streams and deposited where the stream slows down • Syn: ↑alluvial deposit, ↑alluvium, ↑alluvion • Derivationally related forms: ↑alluvial (for: ↑alluvium) … Useful english dictionary
placer deposit — Natural concentration of heavy minerals caused by the effect of gravity on moving particles. When heavy, stable minerals are freed from their matrix by weathering processes, they are slowly washed downslope into streams that quickly winnow the… … Universalium
placer — I. noun Date: 1579 one that places: as a. one that deposits or arranges b. one of the winners in a competition II. noun Usage: often attributive Etymology: Spanish, from Catalan, submarine plain, from plaza place, from Latin platea broad street… … New Collegiate Dictionary
Dolaucothi Gold Mines — The Dolaucothi Gold Mines (grid reference SN662403), also known as the Ogofau Gold Mine, are Roman surface and deep mines located in the valley of the River Cothi, near Pumsaint, Carmarthenshire, Wales. The gold mines are located within the… … Wikipedia
Аллювиальные россыпи — (a. alluvial placer; н. Alluvialseifen; ф. gоte alluvionnaire, gisement alluvionnaire; и. placer aluvial) пром. скопления зёрен полезных минералов в обломочных отложениях русловой фации Аллювия постоянных и временных водных потоков;… … Геологическая энциклопедия
Novosibirsk Oblast — Новосибирская область (Russian) Oblast … Wikipedia
