gemstone
Moonstone
Orthoclase Feldspar ((K,Na)AlSi3O8)
Hardness: 6.0-6.5 Mohs; Color: Colorless to white with blue/white sheen; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Adularescence (schiller) effect.
- Hardness
- 6
- Color
- Colorless to white with blue/white sheen
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6.0-6.5 Mohs; Color: Colorless to white with blue/white sheen; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions; Adularescence (schiller) effect.
Formation & geological history
Formed in plutonic igneous rocks (granite, syenite) and pegmatites through the intergrowth of orthoclase and albite during cooling.
Uses & applications
Primary use is in jewelry as a gemstone, particularly in rings, pendants, and earrings. Also used in spiritual and metaphysical practices.
Geological facts
The ghostly glow of moonstone is caused by light scattering between microscopic layers of feldspar, a phenomenon known as adularescence. It is the state gem of Florida to commemorate the moon landing.
Field identification & locations
Identify by its unique blue or white billowy light effect (adularescence) when rotated under a light source. Commonly found in Sri Lanka, India, Myanmar, and Madagascar.
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