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] Comendite occurs in the mountains Tibrogargan, Coonowrin, Tunbubudla, Coochin, Saddleback, Tibberoowuccum and Ngungun in the Glass House Mountains, South East Queensland, Australia. The blue colour is caused by very small crystals of riebeckite or arfvedsonite.[3] Comendite also occurs in Sardinia, Corsica, Ascension Island, Ethiopia, Somalia and other areas of East Africa.[2] The 1903 eruption of Changbaishan volcano in north-east China erupted comendite pumice.[4]

Comendite at Lookout 589 in the Glass House Mountains

Comendite derives its name from the area of Le Commende on San Pietro Island in Italy, where the rock type is found.[5]

References
  1. Troll, Valentin R.; Schmincke, Hans-Ulrich (2002-02-01). "Magma Mixing and Crustal Recycling Recorded in Ternary Feldspar from Compositionally Zoned Peralkaline Ignimbrite 'A', Gran Canaria, Canary Islands". Journal of Petrology. 43 (2): 243–270. doi:10.1093/petrology/43.2.243. ISSN 0022-3530.
  2. Iddings, Joseph Paxson, 1913, Igneous rocks: composition, texture and classification, v. 2, pp. 94-96
  3. Rocks and landscapes of the Sunshine Coast by Warwick Willmott, Brisbane: Geological Society of Australia Queensland Division, 2007
  4. Changbaishan volcano, China - facts and information. Retrieved 2013-07-24.
  5. 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.
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