Millosevichite

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
Category	Sulfate mineral
Formula (repeating unit)	Al2(SO4)3
IMA symbol	Msv[1]
Strunz classification	7.AB.05
Crystal system	Trigonal
Crystal class	Rhombohedral (3) H-M symbol: (3)
Space group	R3
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
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	[2][3][4]

Millosevichite is a rare sulfate mineral with the chemical formula Al₂(SO₄)₃.^[3] 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, , Vulcano Island, Lipari, Aeolian Islands, Sicily. It was named for Italian mineralogist Federico Millosevich (1875–1942) of the University of Rome.^[2]

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.^[2][5] It occurs with native sulfur, sal ammoniac, letovicite, alunogen and boussingaultite.^[2]

References[]