Outstanding colorless single crystal aggregate of the extremely rare NH4-Fe-sulphate minerals lonecreekite, sabieite and clairite from the type locality for all of them in Lone Creek Falls, Sabie, Southafrica. Ex Vandenbroucke Museum collection from Waregem, Belgium. Analyzed specimen by the former owner of the specimen. — Photo: David Hospital · CC BY 4.0
Lonecreekite
Lonecreekite is an IMA-recognized mineral species in the sulfate class, with the chemical formula (NH₄)Fe³⁺(SO₄)₂·12H₂O.
It crystallizes in the cubic crystal system (space group Pa3). It is a member of the Alum structural group.
Key properties: specific gravity 1.693; Vitreous luster.
IMA symbol Lck, IMA status: approved, named in 1982.
A rare secondary mineral probably produced through alteration of pyrite and reaction, at pH < 1, with ammonia fumes produced as the result of decay of organic matter (Hyrax excreta).
It is found associated with Clairite, sabieite, tschermigite.
The name refers to Lone Creek Fall Cave, South Africa, its original occurrence.