Rock Identifier
Sunstone (Oligoclase (Feldspar variety), (Na,Ca)(Si,Al)4O8) — mineral
mineral

Sunstone

Oligoclase (Feldspar variety), (Na,Ca)(Si,Al)4O8

Hardness: 6-6.5 on Mohs scale; Color: Warm red, orange, or gold with metallic flashes; Luster: Vitreous to sub-vitreous; Crystal structure: Triclinic; Cleavage: Perfect in two directions; Schiller effect (aventurescence).

Hardness
6-6
Color
Warm red, orange, or gold with metallic flashes
Luster
Vitreous to sub-vitreous
Identified More mineral

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Warm red, orange, or gold with metallic flashes; Luster: Vitreous to sub-vitreous; Crystal structure: Triclinic; Cleavage: Perfect in two directions; Schiller effect (aventurescence).

Formation & geological history

Formed in igneous or metamorphic rocks through the crystallization of magma or lava. The characteristic shimmer is caused by tiny inclusions of copper or hematite plates that reflect light.

Uses & applications

Primary use is in the gemstone and jewelry industry as cabochons or faceted stones. It is also a popular collector's mineral.

Geological facts

Oregon Sunstone is unique because its shimmer is caused by copper, while sunstones from other regions typically get their flash from hematite or goethite. It became the official state gemstone of Oregon in 1987.

Field identification & locations

Identify by its distinctive metallic 'glitter' (aventurescence) when rotated in light. Often found in basaltic lava flows and pegmatites. High-quality specimens are found in South-Central Oregon, USA, as well as Norway and India.