Pseudobrookite

minerals

oxide

armacolite

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 (Dana).

Localities

At Mount Anakie, Anakie, City of Greater Geelong, Victoria, Australia, pseudobrookite, together with accompanying minerals such as enstatite and titanium-bearing magnetite, formed by sublimation from a vapour phase during cooling of the lavas. The crystals are up to 2 mm in length, and were apparently stable to low temperatures, probably due to high magnesium content (AJM 21.1.27-38).

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

On the Island of Reunion in the Indian Ocean, French, pseudobrookite is a product of hot volcanic gases acting on basalt (Dana).

At Hessen-Brucker, Hessen, Germany, pseudobrookite is a product of hot volcanic gases acting on basalt (Dana).

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

In Uroiu, Transylvania, Romania, pseudobrookite occurs in cavities in andesite with tridymite, hypersthene and garnet (Dana).

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

In the Thomas Range, Utah, USA, pseudobrookite occurs in cavities in rhyolite associated with topaz, bixbyite, hematite, beryl variety red beryl and ilmenite (Dana).

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