Formula: Mg(SO4).4H2O
Hydrated sulphate mineral, rozenite group
Crystal System: Monoclinic
Specific gravity: 2 measured, 2.007 calculated
Hardness: 2 to 3
Streak: White
Colour: White to very pale yellow or pale greeenish white
Solubility: Soluble in water

Sedimentary environments
Hydrothermal environments

Starkeyite is a secondary mineral sometimes found in the oxidised zone of sulphide mineral deposits, resulting from the decomposition of pyrite and marcasite. It may form from the dehydration of hexahydrite (Mindat).


At the Great Konya Basin, Konya Province, Turkey, starkyite is associated with konyaite, blödite, gypsum and halite (HOM).

At the Alta Mine, Low Divide, Low Divide Mining District, Klamath Mountains, Del Norte County, California, USA, a starkeyite-bearing specimen was collected in a dump area at the now-defunct troilite mine. The starkeyite occurs mainly as a cream-coloured fine-grained efflorescence on troilite, but also forms veins in it (CM 12.3.229-229). At the type locality, the Starkey Mine, Madison County, Missouri, USA, starkeyite occurs as a dull white powdery efflorescence on dump material from a pyrite deposit in dolomite (Mindat).

At the Goldstrike Mines, Nevada, USA, starkeyite is associated with szomolnokite and gunningite (HOM).

Back to Minerals