Comendite Explained

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.[3] The 1903 eruption of Changbaishan volcano in northeast China erupted comendite pumice.[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.[2]

Notes and 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. en. 43. 2. 243–270. 10.1093/petrology/43.2.243. 0022-3530. free.
  2. [Joseph P. Iddings|Iddings, Joseph Paxson]
  3. Rocks and landscapes of the Sunshine Coast by Warwick Willmott, Brisbane: Geological Society of Australia Queensland Division, 2007
  4. http://www.volcanodiscovery.com/changbaishan.html Changbaishan volcano, China - facts and information
  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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