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Formula: (Fe3+2Ti)O5
Multiple oxide, forms a series with armalcolite
Crystal System: Orthorhombic
Specific gravity: 4.33 to 4.39 measured, 4.39 calculated
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,
enstatite-ferrosilite 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,
enstatite-ferrosilite
and garnet
(Dana).
At Red Cone, Crater Lake, Oregon, USA, pseudobrookite occurs in cavities in
basalt with
enstatite-ferrosilite and
apatite.
In the Thomas Range, Utah, USA, pseudobrookite occurs in cavities in
rhyolite associated with topaz,
bixbyite-(Mn), hematite, beryl variety
red beryl and ilmenite
(Dana).
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