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Formula: Ca8(SiO4)2(Si3O10)
Sorosilicate (Si2O7 groups)
Crystal system: Orthorhombic
Specific gravity: 2.97 measured, 2.997 calculated
Hardness: 6 to 6½
Streak: White
Colour: White
Luminescence: Not fluorescent under UV
Environments
Localities
There are two co-type localities, the Birkhin gabbro massif, Narin-Kunta, Irkutsk Oblast, Russia and Xenolith no. 1,
Lakargi Mountain, Upper Chegem volcanic caldera, Chegemsky District, Kabardino-Balkaria, Russia.
Pavlovskyite from both localities has the same composition and physical properties. It is colourless in thin
section. In hand specimens it is white with a white streak and transparent with vitreous lustre
(AM 97.4.503-512).
At the Birkhin gabbro massif, Narin-Kunta, Irkutsk Oblast, Russia, pavlovskyite was detected in altered
silicate-carbonate xenoliths a few meters across. The pavlovskyite forms in symmetric veins cutting
calcio-olivine skarn. The
central part of these veins is composed of galuskinite and its
low-temperature alteration products. Selvages consist of sub-parallel aggregates of fibrous pavlovskyite
crystals, up to 0.3–0.4 mm in length, 10–30 µm thick, nucleating at the vein walls, and
dellaite, filling space between pavlovskyite crystals and separating
them from calcio-olivine. Occasionally,
galuskinite veins are partially replaced by
spurrite, or vice versa, and have a margin composed of pavlovskyite
spherolites growing into calcio-olivine. Rare amoeba-like,
highly-fractured grains of pavlovskyite up to 2 mm in size occur in
calcio-olivine. The following minerals are noted in Birkhin skarns:
calcio-olivine,
galuskinite, larnite,
bredigite, merwinite,
monticellite, spurrite,
kilchoanite, dellaite,
cuspidine,
hydroxylellestadite,
spinel, magnetite, members of the
gehlenite-åkermanite series,
garnet of the grossular
- andradite - schorlomite
- kerimasite series,
baghdadite, chlorbartonite,
pyrrhotite, clintonite,
fluorapatite,
hydroxylapatite,
hillebrandite, perovskite,
wollastonite and vesuvianite.
The development of retrograde
monticellite-dellaite
intergrowths is characteristic of
merwinite-gehlenite
high-temperature skarns at Birkhin. In retrograde
kilchoanite skarns
containing merwinite and
gehlenite,
pavlovskyite and monticellite
intergrowths formed; subsequently pavlovskyite was replaced
by dellaite
(AM 97.4.503-512).
Pavlovskyite from the Birkhin Gabbro Massif -
Image
At Xenolith no. 1, Lakargi Mountain, Upper Chegem volcanic caldera, Chegemsky District, Kabardino-Balkaria, Russia,
pavlovskyite was discovered in the altered carbonate xenolith number 3 (sic). The high-temperature rocks in
which pavlovskyite was found are skarned carbonate xenoliths.
Lakargi Mountain is the type locality of lakargiite,
megawite, chegemite,
kumtyubeite,
calcio-olivine, vorlanite,
toturite, irinarassite,
bitikleite, elbrusite,
magnesioneptunite and
rusinovite.
Pavlovskyite was detected as irregular grains in their characteristic skeletal form within
cuspidine zones of the skarn
with larnite relics. Larnite zones,
replaced by cuspidine, toward the contact with slightly altered
ignimbrite are transformed to
rankinite-wollastonite zones.
In these zones pavlovskyite develops on rankinite
pseudomorphs after quartz
phenocrysts of the ignimbrite. This is especially evident for grains of
partially replaced quartz on the boundary between
skarn and ignimbrite. Here,
pavlovskyite is associated with rusinovite, which also develops
after rankinite.
Early high-temperature minerals such as larnite,
rankinite, wollastonite,
wadalite, rondorfite,
kerimasite, tazheranite,
baddeleyite, lakargiite,
perovskite, apatite and
magnesioferrite are preserved in association with
pavlovskyite in skarns.
Secondary minerals include
trabzonite, killalaite,
hydrogarnet, hillebrandite,
afwillite,
tobermorite-like minerals,
jennite,
thaumasite-ettringite and
hydrocalumite
(AM 97.4.503-512).
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