Yellow crystals of the very rare sulphate mineral clinoungemachite from the type locality in Chuquicamata, Chile. Probable monoclinic dimorph of ungemachite. Ex Vandenbroucke Museum collection specimen, from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Clinoungemachite
Clinoungemachite is an IMA-recognized mineral species in the sulfate class, with the chemical formula K₃Na₈Fe³⁺(SO₄)₆(OH)₂·10H₂O.
Key properties: Vitreous luster.
IMA symbol Cug, grandfathered status — known before the IMA’s founding, named in 1938.
Very rarely formed by the oxidation of pyrite in an arid climate, in veins and cavities in other massive iron sulfates.
It is found associated with Ungemachite, jarosite, sideronatrite, metasideronatrite, metavoltine, fibroferrite.
As the probable monoclinic dimorph of ungemachite.