Pink violet crystals of the rare mineral goldichite from the type locality in Utah (San Rafael District, Emery County, Utah, United States of America). Ex Vandenbroucke Museum collection specimen, from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Goldichite
Goldichite is an IMA-recognized mineral species in the sulfate class, with the chemical formula KFe³⁺(SO₄)₂·4H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: Mohs hardness 2.5; specific gravity 2.43; White streak; Vitreous luster; optically biaxial.
IMA symbol Gol, grandfathered status — known before the IMA’s founding, named in 1955.
Cementing fragments in slope debris from an oxidizing pyritiferous Colorado Plateau-type uranium deposit (Dexter No. 7 mine, Utah, USA).
It is found associated with Alunogen, coquimbite, copiapite, halotrichite (Dexter No. 7 mine, Utah, USA); metavoltine, hexahydrite, ferrinatrite, krausite, halotrichite, voltaite, sulfur.
The mineral was named to honor Dr. Samuel Stephen Goldich (1909–2000), American mineralogist, petrologist, and analytical isotope chemist, Professor of Geology, University of Minnesota, Minneapolis.