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chalk
A soft, earthy, fine-textured, usually white to light-gray or buff limestone of marine origin. It consists almost wholly (90% to 99%) of calcite, formed mainly by shallowwater accumulation of calcareous remains of floating microorganisms (chiefly foraminifers) and of comminuted remains of calcareous algae, set in a structureless matrix of very finely crystalline calcite. The rock is porous, somewhat friable, and only slightly coherent.
- 词性: noun
- 行业/领域: 采矿
- 类别 一般矿业; Mineral mining
- Government Agency: USBM
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创建者
- ed.young
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(Milwaukee, United States)