perthite
perthite

Perthite Value, Price, and Jewelry Information


Perthite is a blend of microcline, albite and oligoclase. It is usually brown and white. May have gold or white iridescence.  

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Perthite is a blend of microcline, albite and oligoclase. It is usually brown and white. May have gold or white iridescence.

 

perthite
Perthite Feldspar from Dan Patch pegmatite, Black Hills, South Dakota. By Jstuby at en.wikipedia (Transferred from en.wikipedia) [Public domain], from Wikimedia Commons

Comments

Perthite is an intergrowth of albite, oligoclase, plus orthoclase or microcline. The characteristic texture is produced by unmixing from high temperature. The appearance of the material depends on the cooling history, and hence the relative crystal sizes of the different feldspars in the mixture. Usually perthite consists of brown and white lamellae; the white feldspar often has a golden yellow or white Schiller. Perthitic intergrowths are very typical of the whole range of plagioclase compositions and therefore must be considered one of the most abundant mineral associations in nature.

Name

Perthite is named for the locality, Perth, Ontario, Canada.

Occurrence

Fine perthite that is suitable for cutting comes from Dungannon Township, Ontario, Canada,in large pieces, and from various localities in Quebec, as well as from other countries.


Joel E. Arem, Ph.D., FGA

Dr. Joel E. Arem has more than 60 years of experience in the world of gems and minerals. After obtaining his Ph.D. in Mineralogy from Harvard University, he has published numerous books that are still among the most widely used references and guidebooks on crystals, gems and minerals in the world.

Co-founder and President of numerous organizations, Dr. Arem has enjoyed a lifelong career in mineralogy and gemology. He has been a Smithsonian scientist and Curator, a consultant to many well-known companies and institutions, and a prolific author and speaker. Although his main activities have been as a gem cutter and dealer, his focus has always been education. joelarem.com

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