Gahnite

Gahnite, ZnAl2O4, is a rare mineral belonging to the spinel group. It forms octahedral crystals which may be green, blue, yellow, brown or grey. It often forms as an alteration product of sphalerite in altered massive sulphide deposits such as at Broken Hill , Australia. Other occurrences include Falun where it is found in pegmatites , Charlemont, Massachusetts ; Spruce Pine, North Carolina ; White Picacho district, Arizona ; and Franklin, New Jersey in the United States

It was first described in 1807 for an occurrence in the Falu mine, Falun, Dalarna, Sweden, and named after the Swedish chemist, Johan Gottlieb Gahn (1745–1818), the discoverer of the element manganese It is sometimes called zinc spinel.