noun
glauconite
A greenish mineral of the mica group, commonly found in marine sedimentary rocks. Technical term used in geology and mineralogy.
この砂岩には海緑石が多く含まれている。
This sandstone contains a lot of glauconite.
From 海 (kai, 'sea') + 緑 (ryoku, 'green') + 石 (seki, 'stone'), referring to its green color and marine origin. The exact historical derivation is uncertain; the spelling is conventionally associated with the mineral.