Schreyerite

schreyerite

rutile

eskolaite

karelianite

Images

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

Metamorphic 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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