What is "stilpnomelane"

Stilpnomelane \Stilp*nom"e*lane\, n. [Gr. stilpno`s shining + me`las, -anos, black.] (Min.) A black or greenish black mineral occurring in foliated flates, also in velvety bronze-colored incrustations. It is a hydrous silicate of iron and alumina.

n. (context mineralogy English) A metamorphic phyllosilicate mineral of the mica group, having the chemical formula K(Fe²⁺,Mg,Fe³⁺)₈(Si,Al)₁₂(O,OH)₂₇.

Stilpnomelane is a phyllosilicate mineral. It has the formula K(Fe,Mg,Fe)(Si,Al)(O,OH)·n(HO).

Stilpnomelane occurs associated with banded iron formations. It is a metamorphic mineral associated with the blueschist and greenschist facies.

It was first described in 1827 for an occurrence in Moravia in the Czech Republic. The name is derived from the Greek stilpnos for shining, and melanos for black.