Millosevichite

Millosevichite is a rare sulfate mineral with the chemical formula Al2(SO4)3.[2] Aluminium is often substituted by iron. It forms finely crystalline and often porous masses.

Millosevichite
Porous yellow Millosevichite. Dimensions: 14 mm x 10 mm x 8 mm. Locality: Kladno Mine (Nejedlý I Mine; Zdeněk Nejedlý Mine; Schoeller Mine; Schöller Mine), Libušin, Kladno, Central Bohemia Region, Bohemia (Böhmen; Boehmen), Czech Republic.
General
CategorySulfate mineral
Formula
(repeating unit)		Al2(SO4)3
Strunz classification7.AB.05
Crystal systemTrigonal
Crystal classRhombohedral (3)
H-M symbol: (3)
Space groupR3
Unit cella = 8.05 Å, c = 21.19 Å; Z = 6
Identification
ColorIndigo, bright red, brick-red
Crystal habitGranular aggregates of minute crystals; stalactitic porous masses
Mohs scale hardness1.5
LusterVitreous
DiaphaneitySemitransparent
Specific gravity1.72 measured
Optical propertiesUniaxial (+)
Refractive indexnω = 1.500 nε = 1.515
Birefringenceδ = 0.015
Other characteristicsHygroscopic
References[1][2][3]

It was first described in 1913 for an occurrence in Grotta dell'Allume, Porto Levante, Vulcano Island, Lipari, Aeolian Islands, Sicily. It was named for Italian mineralogist Federico Millosevich (1875–1942) of the University of Rome.[1]

The mineral is mainly known from burning coal dumps, acting as one of the main minerals forming sulfate crust. It can be also found in volcanic solfatara environments.[1][4] It occurs with native sulfur, sal ammoniac, letovicite, alunogen and boussingaultite.[1]

References
  1. Handbook of Mineralogy
  2. Mindat
  3. Webmineral
  4. Chesnokov B. V. and Shcherbakova E. P. 1991: Mineralogiya gorelykh otvalov Chelyabinskogo ugolnogo basseina - opyt mineralogii tekhnogenesa. Nauka, Moscow


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