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Formula: (Ta2/3Mn2+1/3)O2
Multiple oxide of tantalum and
manganese, ixiolite group,
columbite supergroup
Crystal System: Orthorhombic
Data for old "ixiolite" which has been split into ixiolite-(Fe2+) and ixiolite-(Mn2+):
Specific gravity: 7.03 to 7.23 measured, 7.39 calculated
Hardness: 6 to 6½
Streak: Brown to dark brown
Colour: Steel-grey, black
Environments
Ixiolite occurs in tantalum-bearing
granitic
pegmatites. Heating above 700°C induces order; either to
wodginite structure or to
columbite structure, depending on chemistry
(Mindat).
Localities
First recorded locality is Skogsböle, Kimitoön Island, Kimitoön, Southwest Finland, where ixiolite occurs in a
granitic
pegmatite
(Mindat).
At the SK Star #2 Mining Claim, The Cove, Topaz Mountain, Thomas Range, Juab County, Utah, USA,
topaz occurs
in rhyolite. The topaz is
typically black in colour because of
numerous dark inclusions of ixiolite, but sherry-coloured, grey and colourless
topaz crystals are also
occasionally found. Analysis of thin sections of inclusions in
the topaz indicates the presence of
tungsten-rich
ixiolite, magnetite,
fluorite and fluorannite.
Calcium-fluorine-rich fluid inclusions were also observed
(MinRec 51.6.809-810).
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