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出典:Wiktionary
From iron + stone.
ironstone (countable かつ uncountable, 複数形 ironstones)
出典:Wikipedia
出典:『Wikipedia』 (2010/12/04 19:08 UTC 版)
Ironstone is a fine-grained, heavy and compact sedimentary rock. Its main components are the carbonate or oxide of iron, clay and/or sand. It can be thought of as a concretionary form of siderite. Ironstone also contains clay, and sometimes calcite and quartz.
ironstone