Comendite
“Peralkaline rhyolite from rift zones”
Comendite is a peralkaline rhyolite — a silica-rich volcanic rock unusually enriched in sodium and potassium. It typically forms in continental rift zones and oceanic island settings, often as dramatic obsidian-like flows or as the explosive products of caldera-forming eruptions.
alkali feldspar, quartz, aegirine, arfvedsonite, aenigmatite, volcanic glass
San Pietro (Sardinia, Italy), Pantelleria (Italy), East African Rift, Ascension Island, Socorro Island (Mexico)
6-6.5
Comendite is named after the village of Comende on the Italian island of San Pietro, where these unusual sodium-rich lavas were first described in the 19th century.
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