Comendite

Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite.

[1] Phenocrysts are sodic sanidine with minor albite and bipyramidal quartz.

[2] The blue colour is caused by very small crystals of riebeckite or arfvedsonite.

[4] Comendite derives its name from the area of Le Commende on San Pietro Island in Italy, where the rock type is found.

[5] 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.