Mt. Erebus is the only active volcano in Antarctica. Samples from Erebus Volcano are difficult to acquire, but here are two anorthoclase crystals weathered & eroded from lava exposed on the summit cone.
The summit cone of Erebus has a nice anorthoclase phenocryst gravel lag. Erebus erupts kenyte, the 2nd-rarest lava type on Earth (see also Mt. Kenya volcano). Kenyte is a porphyritic phonolite having anorthoclase feldspar phenocrysts and a glassy to cryptocrystalline groundmass. The kenyte from which these anorthoclase crystals are derived is highly vesiculated and glassy. There's a coating of that material on the crystals shown below.
Erebus is a 1.3 million year old, polygenetic stratovolcano in the West Antarctic Rift System. It has erupted basanite, trachyte, tephriphonolite, and phonolite (kenyte) lavas during its history.
Locality: Mt. Erebus Volcano, western Ross Island, Ross Sea, Antarctica (77º 31’ 51” South, 167º 08’ 40” East).
Anorthoclase phenocrysts ((Na,K)AlSi3O8) having a weathered, highly vesiculated, glassy phonolite coating (kenyte). These are from a phenocryst lag deposit on the summit cone of Mt. Erebus Volcano. The lava from which these crystals derive is Late Pleistocene or Holocene in age (I'm not sure which).
Anorthoclase phenocryst derived from kenyte lava erupted from Mt. Erebus Volcano, Antarctica.