It has the chemical formula K(Fe2+,Mg,Fe3+)8(Si,Al)12(O,OH)27·n(H2O).

[4] Stilpnomelane occurs associated with banded iron formations.

It is a metamorphic mineral associated with the blueschist and greenschist facies.

The name is derived from the Greek stilpnos for shining, and melanos for black.

This article about a specific silicate mineral is a stub.