ピッチストーン

noun

pitchstone

A geological term for a type of volcanic glass with a resinous luster, similar to obsidian but containing more water. Used mainly in scientific contexts.

• ピッチストーンは、黒こく曜よう石せきに似にた天てん然ねんガラスの一いっ種しゅです。

  Pitchstone is a type of natural glass similar to obsidian.