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Formula: Ca2(PO4)Cl
Anhydrous phosphate
Crystal System: Orthorhombic
Specific gravity: 2.98 calculated
Hardness: 4
Streak: White
Colour: Colourless
Luminescence: Goryainovite has a bright orange cathodoluminescence, easy distinguishable from the pale blue
cathodoluminescence of co-existing hydroxylapatite. Synthetic
Ca2(PO4)Cl fluoresces pale orange under 254 nm UV radiation and does not fluoresce under
385 nm UV (AM 106.161-162).
Environments
Goryainovite was approved in 2016 and to date (June 2022) it has been reported only from the type locality.
Localities
At the type locality, Stora Sahavaara, Sahavaara, Pajala, Norrbotten County, Sweden, iron ore lenses up to 1.3 km
long and 80 m thick are situated at the contact greenstone rocks
(metamorphosed conglomerate,
quartzite,
banded iron formation, black
schist, dolostone,
phyllite,
tholeiitic lava and
tuff, and dolerite) in
the footwall and medium-grade metamorphosed volcanic and sedimentary rocks in the hanging wall. Host
diopside-amphibole
skarn gradually transforms into a
magnetite-serpentine rock
with relics of diopside,
tremolite, phlogopite and
newly formed chlorite,
pyrrhotite, pyrite,
chalcopyrite and
valleriite.
Goryainovite was found in one specimen as small rounded grains up to 20 μm included in anhedral
magnetite grains up to 1 mm in
serpentine pseudomorphs
after diopside with pyrrhotite,
chalcopyrite and chlorine-rich
hydroxylapatite. The
magnetite commonly contains octahedral inclusions up to 10 μm of
spinel and, rarely, of anhydrite,
thorianite, dolomite and
magnesite.
Goryainovite is an early-formed phosphate. When chlorine fugacity (effective partial pressure) decreased,
goryainovite was transformed into
chlorapatite–hydroxylapatite,
and only grains isolated in magnetite remained unaltered
(AM 106.161-162).
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