Perthite Value, Price, and Jewelry Information

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

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


Perthite Value

The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.

Perthite Information

Is a Variety ofFeldspar
Crystallography Triclinic.
Colors Brown, white.
Luster Vitreous.
Fracture Conchoidal, uneven, splintery
Hardness 6-6.5
Specific Gravity 2.57-2.69
Cleavage Perfect 2 directions
Transparency Transparent.
Phenomena Iridescence, schiller.


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.


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


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.