ob·sid·i·an /əbˈsɪdiən/
黑曜石,十勝石
ob·sid·i·an n. Min. A kind of glass produced by volcanoes. It is usually of a black color, and opaque, except in thin splinters.
Note: ☞ In a thin section it often exhibits a fluidal structure, marked by the arrangement of microlites in the lines of the flow of the molten mass.
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obsidian
n : acid or granitic glass; usually dark, but transparent in
thin pieces