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Formula: Ca3(PO4)2
Anhydrous normal phosphate, tuite group, high-pressure mineral
Crystal System: Trigonal
Specific gravity: 3.452 calculated
Streak: White
Colour: Colourless to white
Environments
Localities
At the type locality, the Suizhou meteorite, Xihe, Zengdu District, Suizhou, Hubei, China, tuite was found in
a shock melt vein of the chondrite. It occurs as
polycrystalline aggregates in association with coarse-grained aggregates of
ringwoodite, majorite and
NaAlSi3O8-hollandite. These high-pressure mineral
assemblages are enclosed in the fine-grained matrix of the vein that consists of
majorite-pyrope, FeNi metal and
troilite.
The tuite is colourless and transparent with vitreous lustre and a white streak.
Tuite in the shock vein of this meteorite was transformed from
whitlockite via a shock-produced solid-state reaction, while the pressure
and temperature in the shock vein reached 23 GPa and 2000°C
(EJM 15.1001-1005).
At the Zagami Martian meteorite, Faskari, Katsina, Nigeria, the high-pressure minerals tuite and
ahrensite are located in two small shock-induced melt pockets in the
meteorite, coexisting with granular and acicular stishovite and
seifertite. Tuite may be formed by decomposition of
apatite or by transformation of
merrillite under high pressure and temperature conditions.
Chlorine-bearing products, presumably derived from the decomposition of
apatite, are concentrated along the grain boundaries of tuite grains.
Nanocrystalline ahrensite found in a
pyroxene clast is likely to be a decomposition product of
pigeonite under high pressure and temperature conditions by a
solid-state transformation mechanism
(AM 107.6.1018–1029).
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