A hard, dense, dark volcanic rock composed chiefly of plagioclase, pyroxene, and olivine, and often having a glassy appearance.

一种硬的、致密的、黑色的火山岩。它主要由斜长石、辉石和橄榄石组成，外表经常很光滑。

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This glassy one is found in volcanic rock. In fact, I found it in New Mexico on a collecting trip.

这个像玻璃一样的矿石是在火山石里面发现的，实际上，我是在新墨西哥州收集旅行中发现的。

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