Pseudobrookite

oxide

tridymite

Formula: (Fe3+2Ti)O5 multiple oxide, member of the armacolite-pseudobrookite series
Specific gravity: 4.39
Hardness: 6
Streak: Reddish brown to ochre yellow
Colour: Black, dark reddish brown
Solubility: Soluble in hot hydrochloric and sulphuric acid
Environments:

Volcanic igneous environments
Volcanic sublimates
Basaltic cavities

Pseudobrookite is usually formed from hot vapours in volcanic rocks, associated with tridymite, hematite, magnetite, sanidine, apatite and rutile.

Localities

France

At Riveau Grande, Puy de Dome, pseudobrookite occurs in cavities in andesite with tridymite, hypersthene and sanidine.

On the Island of Reunion in the Indian Ocean it is a product of hot volcanic gases acting on basalt.

Germany

At Hessen-Brucker, Hessen, it is a product of hot volcanic gases acting on basalt.

Italy

Pseudobrookite occurs on lava from the 1872 eruption of Vesuvius with hematite, magnetite and sellaite.

Romania

In Uroiu, Transylvania, pseudobrookite occurs in cavities in andesite with tridymite, hypersthene and garnet.

USA

At Red Cone, Crater Lake, Oregon, pseudobrookite occurs in cavities in basalt with hypersthene and apatite.

In the Thomas Range, Utah, pseudobrookite is occurs in cavities in rhyolite associated with topaz, bixbyite, hematite, red beryl and ilmenite.

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