玉ぎょく髄ずい

noun

chalcedony

A mineral term for a cryptocrystalline form of silica; used in geology and gemology.

• 玉ぎょく髄ずいは石せき英えいの一いっ種しゅで、瑪め瑙のうや碧へき玉ぎょくなども含ふくまれる。

  Chalcedony is a type of quartz, and includes agate and jasper.