Millosevichite

Millosevichite
General
Category Sulfate mineral
Formula
(repeating unit)		 Al2(SO4)3
Strunz classification 07.AB.05
Crystal system Trigonal
Unit cell a = 8.05 Å, c = 21.19 Å; Z=6
Identification
Color Indigo, bright red, brick-red
Crystal habit Granular aggregates of minute crystals; stalactitic porous masses
Crystal symmetry Trigonal rhombohedral
H-M symbol: (3) Space Group: R3
Mohs scale hardness 1.5
Luster Vitreous
Diaphaneity Semitransparent
Specific gravity 1.72 measured
Optical properties Uniaxial (+)
Refractive index nω = 1.500 nε = 1.515
Birefringence δ = 0.015
Other characteristics Hygroscopic
References [1][2][3]

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.

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. 1 2 3 4 Handbook of Mineralogy
  2. 1 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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