Pantellerite is a type of volcanic rock, specifically a peralkaline rhyolite. It has a higher iron and lower aluminium composition than comendite. It is named after Pantelleria, a volcanic island in the Strait of Sicily and the type location for this rock. On Pantelleria the rock is usually found as a vitrophyre containing phenocrysts of anorthoclase or sanidine. Quartz is found only in the most strongly peralkaline rocks. Mafic minerals may include aegirine, fayalite, aenigmatite, ilmenite, and sodic amphibole (often arfvedsonite or ferrorichterite).
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In this Dossier
Arfvedsonite in the context of Comendite
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite. Phenocrysts are sodic sanidine with minor albite and bipyramidal quartz. The blue colour is caused by very small crystals of riebeckite or arfvedsonite. The 1903 eruption of Changbaishan volcano in northeast China erupted comendite pumice.
Comendite derives its name from the area of Le Commende on San Pietro Island in Italy, where the rock type is found. Comendite also occurs in the Glass House Mountains of southeast Queensland, Australia, as well as in Sardinia, Corsica, Ascension Island, Ethiopia, Somalia and other areas of East Africa.