English: Dolerite ventifact from Antarctica. (United States Polar Rock Repository collection, Byrd Polar Research Center, Ohio State University, Columbus, Ohio, USA)

Ventifacts are lustrous, polished rocks with subplanar to curved facets. They form by natural abrasion and polish by winds that carry sand grains. Ventifacts are naturally sand-blasted rocks.

The rock itself is dolerite, also known as diabase. It is the shallow intrusive equivalent of basalt. Specimen-wise, it is essentially identical to basalt - a mafic, aphanitic igneous rock composed of plagioclase feldspar and pyroxene.

Geologic unit: unrecorded/undisclosed, but almost certainly derived from the Ferrar Dolerite, Jurassic

Locality: unrecorded/undisclosed site in Antarctica (but very likely from the Dry Valleys west of McMurdo Sound, possibly Taylor Valley)