What is "caryopilite"

n. (context mineral English) A monoclinic mineral containing arsenic, chlorine, hydrogen, iron, magnesium, manganese, oxygen, silicon, and zinc.

Caryopilite (synonymous with ectropite and ektropite) is a brown-colored mineral with formula (Mn,Mg)SiO(OH). The mineral was discovered in 1889 from a mine in Sweden. It was named for the Greek words for walnut and felt in reference to its appearance.