mineral
Sunstone (Feldspar)
Plagioclase / Potassium Feldspar (KAlSi3O8 / (Na,Ca)Al1-2Si2-3O8)
AI-generated identification · may be incorrectHardness: 6-6.5 Mohs scale. Color: Peach, salmon pink, orange-brown with schiller effect. Luster: Vitreous to pearly. Crystal structure: Triclinic. Cleavage: Perfect in two directions intersecting at nearly 90 degrees. Specific gravity: 2.56-2.62.
- Hardness
- 6-6
- Color
- Peach, salmon pink, orange-brown with schiller effect
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-6.5 Mohs scale. Color: Peach, salmon pink, orange-brown with schiller effect. Luster: Vitreous to pearly. Crystal structure: Triclinic. Cleavage: Perfect in two directions intersecting at nearly 90 degrees. Specific gravity: 2.56-2.62.
Formation & geological history
Forms in igneous rocks, particularly in basalt flows or pegmatites, where copper or hematite inclusions align parallel to crystal planes as the magma cools and crystallizes.
Uses & applications
Popular as a gemstone for jewelry making (cabochons, beads, rings), as well as being widely collected as a tumbled specimen and used in ornamental carvings.
Geological facts
The shimmering effect in sunstone is called aventurescence or 'schiller', which is caused by light reflecting off tiny microscopic platelets of hematite, copper, or goethite inside the mineral.
Field identification & locations
Identified by its characteristic salmon-pink to orange hue with subtle glistening reflections under direct light and distinct feldspar cleavage lines. Frequently found in India, Norway, Madagascar, Russia, and the United States (Oregon).
