mineral
Sunstone
Plagioclase Feldspar (Oligoclase or Andesine) - (Na,Ca)(Si,Al)3O8
Hardness: 6.0-6.5 on the Mohs scale. Color: Peach, pink, orange, or reddish-brown with a schiller sheen. Luster: Vitreous to pearly. Crystal Structure: Triclinic. Cleavage: Perfect in two directions at nearly 90 degrees. Specific Gravity: 2.62-2.65.
- Hardness
- 6
- Color
- Peach, pink, orange, or reddish-brown with a schiller sheen
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6.0-6.5 on the Mohs scale. Color: Peach, pink, orange, or reddish-brown with a schiller sheen. Luster: Vitreous to pearly. Crystal Structure: Triclinic. Cleavage: Perfect in two directions at nearly 90 degrees. Specific Gravity: 2.62-2.65.
Formation & geological history
Formed in igneous pegmatites and basaltic lava flows where copper or hematite micro-inclusions crystallize in parallel alignments during slow cooling, creating an aventurescent optical phenomenon.
Uses & applications
Used primarily as a gemstone for jewelry (cabochons, beads, and facets) and as decorative mineral specimens for lapidary artists and collectors.
Geological facts
The optical shimmering effect seen in sunstone is called aventurescence or schiller, caused by tiny reflective platelets of hematite, goethite, or metallic copper within the feldspar lattice. Oregon Sunstone, which contains micro-copper inclusions, is the official state gemstone of Oregon.
Field identification & locations
Look for the metallic, glittery flash (schiller effect) when rotating the stone under light. Highly valued locations include Oregon (USA), India, Madagascar, Norway, and Canada. Clean with warm soapy water and avoid harsh chemicals or ultrasonic cleaners.
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