Acta Musei Moraviae

Accesory schreyerite in vanadium-rich graphite quartzite at Bítovánky (Moldanubicum, western Moravia)

A new occurrence of schreyerite was found in graphite quartzite near Bítovánky, in the south-eastern part of the Moldanubian zone (Bohemian Massif). It forms thin lamellae and grains intergrown with vanadium-rich rutile (0.044–0.058 apfu V) and isolated microscopic grains, in mineral assemblage quartz + graphite + vanadium muscovite + vanadium dravite. Schreyerite is poor in Cr and its chemical composition corresponds to the formula (V³⁺_{1.890–1.980}Cr³⁺_{0.020–0.040}Al³⁺_{0.020–0.040})₂(Ti⁴⁺_{2.810–2.850} V⁴⁺_{0.140–0.190})₃ O₉. Schreyerite is locally altered to hydrated TiO₂ with higher contents of Al (≤ 0.060 apfu) and Fe (< 0.028 apfu) compared to the original phase. Schreyerite predominately formed by exsolution from vanadium-rich rutile in the metamorphic post-peak conditions of the upper amphibolite facies.