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Formula: Cu5O2(VO4)2
Anhydrous vanadate
Crystal System: Monoclinic
Specific gravity: 5.0 measured, 4.96 calculated
Streak: Reddish brown
Colour: Black
Luminescence: Not fluorescent under UV
Solubility: Soluble in dilute sulphuric acid
Environments
Localities
The type locality, the Izalco Volcano, Sonsonate Department, El Salvador, is a
basaltic and andesitic
stratovolcano that has been intermittently active since its birth in 1770. In 1963,
shcherbinaite, the first-known high-temperature
vanadium mineral, was discovered in the summit crater fumaroles. Since that
time, five other high-temperature vanadium sublimates have been isolated from
the fumarolic mineral suite. These are bannermanite and four
copper vanadates,
stoiberite, mcbirneyite,
ziesite and fingerite. These
minerals formed as sublimates from vanadium-bearing gases at temperatures up to
760oC.
Stoiberite is found in one of five major fumaroles in the summit crater. ln 1964, when the mineral was first
discovered, the temperature of the fumarole was 450oC. The temperature of the fumarole in Novembet, 1978, had
fallen to 89oC, and only small amounts of stoiberite were found. It occurs as a black incrustation in
the oxide zone of the fumarole. The crystals are less than 100 microns in size and coat
basaltic breccia fragments
(AM 64.941-944).
Stoiberite from the Izalco Volcano -
Image
At the Lichtenberg Absetzer dump, Kauern, Greiz District, Thuringia, Germany, stoiberite has been found
(Mindat photo).
Stoiberite from the Lichtenberg Absetzer dump -
Image
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