mineral

Sunstone

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

Hardness: 6.0-6.5 Mohs. Color: Orange to reddish-brown with metallic flashes. Luster: Vitreous to pearly. Crystal structure: Triclinic. Cleavage: Perfect in two directions. Features 'schiller' or aventurescence caused by copper or hematite inclusions.

Hardness: 6
Color: Orange to reddish-brown with metallic flashes
Luster: Vitreous to pearly

Identified July 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous environments, typically within basaltic lava flows or pegmatites. The aventurine effect is caused by tiny plate-like inclusions of copper, hematite, or goethite that reflect light as the stone is turned.

Uses & applications

Primarily used as a gemstone for jewelry (rings, pendants, earrings) and as a collector's specimen. In industry, feldspars are used in glass and ceramic manufacturing.

Geological facts

Sunstone was once thought to be a compass by Vikings and is the official state gemstone of Oregon. The flashes of light within the stone are known as 'aventurescence'.

Field identification & locations

Identify in the field by its distinct orange metallic glitter (schiller) and feldspar cleavage. Commonly found in Oregon (USA), Norway, Tanzania, and India. Collectors look for high transparency and strong copper flash.