felsőbányaite

{{infobox mineral | name = Felsőbányaite | image = Felsöbanyaite Soria.jpg | alt = | caption = Felsöbanyaite as white spherules. Roadcut near Sant Marti dels Castells (Lérida) Spain | category = Sulfate mineral | formula = Al4(SO4)(OH)10·4H2O | IMAsymbol = Fsb | strunz = 7.DD.05 | dana = | system = Monoclinic | class = Sphenoidal (2) (same H-M symbol) | symmetry = P21 | unit cell = a = 13.026 Å, b = 10.015 Å, c = 11.115 Å; β = 104.34°; Z = 4 | color = White to pale yellow, pale brown | habit = Globular masses, minute rhombic crystals | twinning = | cleavage = Distinct to good on {010} and {100} | fracture = | tenacity = | mohs = 1.5 | luster = Vitreous, pearly on cleavage surfaces | streak = | diaphaneity = Semitransparent | gravity = 2.33 | density = | polish = | opticalprop = Biaxial (+) | refractive = n = 1.515–1.540 | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }} Felsőbányaite or basaluminite is a hydrated aluminium sulfate mineral with formula: Al4(SO4)(OH)10·4H2O. It is a rare white to pale yellow mineral which typically occurs as globular masses and incrustations or as minute rhombic crystals. It crystallizes in the monoclinic crystal system.

It occurs as a weathering product under acidic conditions associated with pyrite or marcasite decomposition. Associated minerals include hydrobasaluminite, hydroargillite, meta-aluminite, allophane, gibbsite, gypsum and aragonite.