BLUE DIOPSIDITE SKARN

Skarn is a coarsely-crystalline, contact metamorphic rock. The attractive rock shown below is a rare variety of skarn dominated by bluish-colored diopside pyroxene (“violane” or “violan”) ((Ca,Mg,Fe)₂Si₂O₆). Such rocks are called diopsidite skarn.

Geologic origin & context & age: magnesium skarn formed by metamorphism of dolostone xenoliths by a gabbro-peridotite layered intrusion, Yoko-Dovyrensky Massif, Neoproterozoic, ~700 Ma.

Locality: Dovyren Highlands, Buryatia Republic, Transbaikalia, eastern Siberia, Russia.

Blue diopsidite skarn (above & below) from the Neoproterozoic of the Dovyren Highlands, eastern Siberia, Russia.

(above: tumble-polished specimen) (below: fresh broken surface of above specimen; ~32 mm across at its widest)

Specimen generously donated by James Cheshire.

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