Oligoclase is a species of plagioclase feldspar. The variety used in jewellery is called sunstone or, less commonly, aventurine feldspar. It has reflective inclusions of red, orange, or green platy crystals, which give it a metallic glitter. Sunstone might be faceted or carved – often as cabochons.
Sunstone occurs in metamorphic and igneous rocks in Norway, United States, India, the former USSR, and Canada.
Aventurescent effect due to reflections from metallic inclusion like hematite, goethite or copper.
Aluminum silicate of potassium, sodium and calcium. KAlSi3O8. Isomorphous series made up of Albite (Na), Oligoclase, Andesine, Labradorite, Bytownite and Anorthite (Ca) where the two end member are NaAlSi3O8 and CaAl2Si2O8.
Triclinic System
Facetted, cabochon, beads and carving.
Platelets of goethite, copper, hematite, fingerprints and crystal inclusions.
Anisotropic, D.R.; Biaxial negative
1.542 – 1.549 / 0.00
Sunstone simulated by aventurine quartz (structure), goldstone glass (inclusions).
U.S.A. (Oregon), India, Kenya, Norway, Russia.
Not characteristic.
None.
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Gemstones are minerals or rocks that are present
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