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.[3][2]

Felsőbányaite
Felsöbanyaite as white spherules. Roadcut near Sant Marti dels Castells (Lérida) Spain
General
CategorySulfate mineral
Formula
(repeating unit)
Al4(SO4)(OH)10·4H2O
IMA symbolFsb[1]
Strunz classification7.DD.05
Crystal systemMonoclinic
Crystal classSphenoidal (2)
(same H-M symbol)
Space groupP21
Unit cella = 13.026 Å, b = 10.015 Å,
c = 11.115 Å; β = 104.34°; Z = 4
Identification
ColorWhite to pale yellow, pale brown
Crystal habitGlobular masses, minute rhombic crystals
CleavageDistinct to good on {010} and {100}
Mohs scale hardness1.5
LusterVitreous, pearly on cleavage surfaces
DiaphaneitySemitransparent
Specific gravity2.33
Optical propertiesBiaxial (+)
Refractive indexn = 1.515–1.540
References[2][3]

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.[3]

Felsőbányaite was first described in 1853 for an occurrence in the Baia Sprie mine, Baia Sprie (Felsőbánya), Maramureș County, Romania, and named for the locality.[2] The mineral name basaluminite was used for an occurrence of the same mineral in England in 1948 and discredited by the International Mineralogical Association (IMA) in 2006.[4]

References

edit
  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c Felsőbányaite on Mindat.org
  3. ^ a b c Basaluminite in the Handbook of Mineralogy
  4. ^ "Burke, E. A. (2006) A mass discreditation of GQN minerals, The Canadian Mineralogist, 44(6), pp. 1557-1560" (PDF). Archived from the original (PDF) on 2012-03-26. Retrieved 2014-07-29.