Oligoclase

Oligoclase is a species of plagioclase feldspar. The variety used in jewelry is called sunstone or, less commonly, aventurine feldspar. It has reflective inclusions of orange, red, or green platy crystals. These give it a metallic glitter. Sunstone may be carved as cabochons or faceted. The hematite flakes on the rough crystal sometimes produce sparkling parallel bands.

Occurrence

Sunstone occurs in metamorphic and igneous rocks in the former USSR, Norway, the USA, India, and Canada.

Oligoclase Properties

• Specific Gravity: 2.64
• Refractive Index: 1.54-1.55
• Birefringence (DR): 0.007
• Luster: Vitreous
• Crystal Structure: Triclinic
• Composition: Sodium calcium aluminosilicate
• Hardness: 6

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Crystals Directory

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Birthstone

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