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出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/05/11 09:38 UTC 版)
Ball clays are kaolinitic sedimentary clays, that commonly consist of 20-80% kaolinite, 10-25% mica, 6-65% quartz. Localized seams in the same deposit have variations in composition, including the quantity of the major minerals, accessory minerals and carbonaceous materials such as lignite. They are fine-grained and plastic in nature.