comendite
{{short description|Hard, peralkaline igneous rock, a type of light blue grey rhyolite}}
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite.{{Cite journal|last1=Troll|first1=Valentin R.|last2=Schmincke|first2=Hans-Ulrich|date=2002-02-01|title=Magma Mixing and Crustal Recycling Recorded in Ternary Feldspar from Compositionally Zoned Peralkaline Ignimbrite 'A', Gran Canaria, Canary Islands|url=https://academic.oup.com/petrology/article/43/2/243/1550415|journal=Journal of Petrology|language=en|volume=43|issue=2|pages=243–270|doi=10.1093/petrology/43.2.243|issn=0022-3530|doi-access=free}} Phenocrysts are sodic sanidine with minor albite and bipyramidal quartz.Iddings, Joseph Paxson, 1913, Igneous rocks: composition, texture and classification, v. 2, pp. 94-96 The blue colour is caused by very small crystals of riebeckite or arfvedsonite.Rocks and landscapes of the Sunshine Coast by Warwick Willmott, Brisbane: Geological Society of Australia Queensland Division, 2007 The 1903 eruption of Changbaishan volcano in northeast China erupted comendite pumice.[http://www.volcanodiscovery.com/changbaishan.html Changbaishan volcano, China - facts and information]. Retrieved 2013-07-24.
Comendite derives its name from the area of Le Commende on San Pietro Island in Italy, where the rock type is found.Cioni, R. and Funedda, A., (2005) Structural geology of crystal-rich, silicic lava flows: A case study from San Pietro Island (Sardinia, Italy) in Manga, M. and Ventura, G. (editors) (2005) Kinematics and Dynamics of Lava Flows, Geological Society of America Special Paper 396, pages 1 to 14. 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.