mineral

Sunstone

Oligoclase (Plagioclase Feldspar subclass), (Ca,Na)(Al,Si)4O8

AI-generated identification · may be incorrect

Hardness: 6-6.5 (Mohs scale); Color: Orange, reddish-brown, gold; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect in two directions; Specific Gravity: 2.62-2.65; notable for aventurescence (metallic shimmer).

Hardness: 6-6
Color: Orange, reddish-brown, gold
Luster: Vitreous to pearly

Identified April 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous environments (lava flows or pegmatites) and occasionally metamorphic rocks. The shimmer is caused by tiny inclusions of hematite, copper, or goethite that align during cooling.

Uses & applications

Primarily used as a gemstone in jewelry (rings, pendants, earrings), as a collector's mineral, and occasionally in metaphysical practices.

Geological facts

Sunstone was once thought to be a guide for Viking sailors, who used its polarizing properties (as a 'sunspar') to find the position of the sun on cloudy days. It is the official state gemstone of Oregon, USA.

Field identification & locations

Identify in the field by its distinct metallic shimmer ('schiller' effect) when rotated under light, and its orange-pink feldspar base. Found in Norway, Tanzania, Madagascar, and the USA (Oregon).