Rhenium disulfide, an extremely rare mineral found in volcanic fumaroles. It's associated with unique, high-frequency energies and transformation. (The primary natural source of rhenium).
Reddish-Grey, Greyish-Black, often with a metallic luster, (Extremely rare, found in fumaroles)
Rheniite is classified as a sulfide mineral mineral which typically crystallizes in the triclinic system. Its chemical formula is ReS2. Common crystal habits include platey.