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Formula: V3+2Ti4+3O9
Oxide, vanadium- and titanium-
bearing mineral
Crystal System: Monoclinic
Specific gravity: 4.46 calculated
Hardness: 7
Colour: Reddish brown
Solubility: Insoluble in inorganic acids
Environments
Localities
At the Rampura-Agucha Zn-(Pb) deposit, Bhilwara District, Rajasthan, India, the rare
vanadium oxide schreyerite occurs as exsolution lamellae in
rutile. These unusual compositions are attributed to locally high
concentrations of vanadium in the precursor sediments.
Schreyerite forms fine, less than 5 microns, oriented exsolution
larnellae in large grains of rutile
(CM 33.745-752).
At the type locality, Lasamba Hill, Kwale County, Kenya, the host rock consists of alternating layers of
gneiss and quartzite.
The strongly weathered, highly metamorphosed gneiss contains
quartz, biotite,
tourmaline, diopside and
epidote. The most abundant opaque minerals are
graphite and rutile, although traces
of pyrrhotite, chalcopyrite
and pentlandite are also found.
Schreyerite always occurs in intergrowth with rutile.
The rutile grains in the gneiss
reach up to 0.5 mm across, and are partly idiomorphic (having its own proper form). The ratio of
schreyerite to rutile is strongly variable. In one section,
rutile crystals devoid of schreyerite coexist with others
predominantly schreyerite
(AM 63.1182-1186).
The gneiss formed above 600oC and 5 kbar pressure. Associated
minerals include vanadium-bearing
rutile, kornerupine,
kyanite, sillimanite,
muscovite, apatite,
tourmaline, graphite,
pyrrhotite, chalcopyrite and
pentlandite
(HOM).
Schreyerite from Lasamba Hill -
Image
At the Green Giant Vanadium Property, Atsimo-Andrefana, Madagascar, the geology mainly consists of
quartzo-feldspathic
gneisses, with bands of
hornblende-biotite
gneiss, marble,
granitoid and
amphibolite. The rocks containing the highest
vanadium contents are
sillimanite- and graphite-
bearing quartzo-feldspathic
gneisses with minor phlogopite,
graphite, pyrite,
muscovite, apatite,
titanite, chalcopyrite,
hematite, and calcite. The
vanadium host minerals in the suite are
roscoelite, rutile,
schreyerite, oxyvanite,
karelianite, an unknown
vanadium-titanium bearing oxide,
pyrrhotite, pyrite,
goldmanite, dravite,
uvite, actinolite, and three
unidentified vanadium-bearing sulphides.
Schreyerite is present as intergrowths within rutile
(CM 56.3.247-257).
At Slyudyanka, Lake Baikal area, Russia, schreyerite has been found in metamorphic rocks. In contrast to
previously known schreyerite lamellae, which are intergrown with rutile,
crystals from the Sludyanka complex occur as isolated single crystals associated with
titanite. A peculiarity of this schreyerite sample is the partial
substitution of V4+ for Ti4+
(AM 91.1.196-202).
Associated minerals include rutile,
eskolaite, karelianite,
vuorelainenite and
olkhonskite
(HOM).
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