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Formula: CaSiO3
Cyclosilicate (ring silicate), monoclinic paramorph of triclinic
breyite, isometric davemaoite
and triclinic wollastonite
Crystal System: Monoclinic
Luminescence: Lilac cathodoluminescence has been reported (Mindat)
Environments
Metamorphic environments
Hydrothermal environments
Pseudowollastonite is well known as an artificial high-temperature phase dimorphous with
wollastonite from slags and cement, but also very rarely found in
nature from pyrometamorphosed calcareous rocks. The structure contains isolated trisilicate rings
(Si3O9)6-
(Mindat).
Localities
At the Gurim anticline, Hatrurim Basin, Tamar Regional Council, Southern District, Israel, two new
barium-bearing minerals, gurimite
and hexacelsian, were discovered in veins of
paralava
cutting gehlenite - flamite
hornfels. Gurimite and
hexacelsian occur in inclusions in
paralava and are associated with
gehlenite, pseudowollastonite or
wollastonite, rankinite,
flamite, larnite,
schorlomite, andradite,
fluorapatite,
fluorellestadite,
kalsilite, cuspidine,
aradite, zadovite and
khesinite
(MM 81.4.1009–1019).
At the Nabi Musafossil mud volcano, Jericho Governorate, West Bank, Palestine, pseudowollastonite, an
extremely rare constituent of ultra high-temperature combustion metamorphic and igneous rocks, has been found as a
rock-forming mineral in calcium-rich paralava veins.
Pseudowollastonite-bearing paralavas are the products of
combustion metamorphism associated with spontaneous burning of methane. The melt began to crystallise at
1480 to 1500°C about the ambient pressure. Pseudowollastonite enters two mineral assemblages:
(1) rankinite, larnite,
nagelschmidtite,
wollastonite,
gehlenite-rich melilite,
titanium-rich andradite,
cuspidine and fluorapatite.
(2) parawollastonite, wollastonite,
gehlenite-rich melilite,
titanium-rich andradite and
fluorellestadite.
It is argued that pseudowollastonite is so scarce in nature because its formation requires joint action of
several uncommon factors: availability of hot melts of T > 1200°C that bear free calcium but are poor in
magnesium and iron (mostly as Fe3+) and their crystallisation in the shallow crust followed by quenching
(Lithos Volumes 134–135, Pages 75-90).
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