Stibnite

Stibnite is very soft, only a 2 on the mohs harness scale, slightly softer than your finger nail. You wouldn’t want to touch stibnite, though, as it is antimony sulfide, and is a poisonous material. Stibnite is primarily used for industrial purposes, such as metal smelting and matches. Because of its softness, when rather large piece was brought to the museum it was put into crate, and then the crate was filled with powder detergent, to hold the delicate crystals in place. Its metallic luster is unusual and attracts collectors. Specimens of this size are rarely found.