What is "coyoteite"

n. (context mineral English) A triclinic black mineral containing hydrogen, iron, oxygen, sodium, and sulfur.

Coyoteite is a hydrated sodium iron sulfide mineral. The mineral was named coyoteite after Coyote Peak near Orick, California where it was discovered (along with another rare mineral, orickite).

This mineral is unstable under normal atmospheric conditions, making it rare at the surface. The mineral was first described in a petrographic study of a sample of a mafic diatreme at Coyote Peak. The largest piece of coyoteite found on that specimen has the dimensions of 0.2 × 0.4 mm.