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Formula: NaAlSi3O8
Tectosilicate (framework silicate), paramorph of
albite and kumdykolite
Crystal System: Tetragonal
Streak: White
Colour: White
Environments
Derived from the Upper Mantle
Meteorites
Lingunite was approved in 2004. It occurs intimately intergrown with
feldspathic glass in shock-induced melt veins.
It is a feldspar group high-pressure
paramorph of plagioclase
believed to be present below 400 km in the Earth's mantle
(Webmin).
Localities
The type locality is the Sixiangkou meteorite, Sixiangkou, Gaogang District, Taizhou, Jiangsu, China. The meteorite is
a heavily shocked low-iron chondrite that contains numerous
shock-induced melt veins. The major high-pressure minerals are majorite and
majorite-pyrope solid solution
minerals. Diopside, akimotoite
and jadeite were also observed.
Diopside coexists with ringwoodite
(+ akimotoite) in coarse-grained fragments of the melt veins.
Majorite occurs as coarse-grained polycrystalline material, formed through
solid state transformation.
Majorite-pyrite fine-grained solid
solution crystallised from a melt under pressure.
Akimotoite coexists with low-calcium
pyroxene in coarse-grained fragments of melt veins.
Fine-grained jadeite originated from retrograde transformation of
lingunite under moderate post-shock pressure and high temperature conditions
(EJM 18.6.719–726).
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