Felsőbányaite
A rare white hydrated aluminium sulfate — also called basaluminite — forming globular masses and minute rhombic crystals.
Intro adapted from Wikipedia (CC BY-SA).
Felsőbányaite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Al₄(SO₄)(OH)₁₀·4H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1).
Key properties: Mohs hardness 1.5; specific gravity 2.33–2.35; Vitreous, pearly on cleavages luster; optically biaxial.
IMA symbol Fsb, grandfathered status — known before the IMA’s founding, named in 1854.
A rare product of oxidation of marcasite ores.
It is found associated with Marcasite, stibnite, barite, quartz.
The name refers to Baia Sprie, Romania (formerly Felsőbánya, Hungary).
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet.
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