a blue-grey sandstone containing much clay, used for building and paving the blue crystalline form of copper sulphate
WordReference Random House Unabridged Dictionary of American English © 2026
blue•stone
(blo̅o̅′stōn′),USA pronunciation n.
- Building, Mininga bluish, argillaceous sandstone used for building purposes, flagging, etc.
- blue + stone 1645–55
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