mineral
Moonstone
Orthoclase feldspar (KAlSi3O8)
Hardness: 6-6.5 Mohs scale, Color: Colorless to white/bluish, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect in two directions, Specific gravity: 2.56-2.59, Adularescence: Blue or white glow
- Hardness
- 6-6
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Physical properties
Hardness: 6-6.5 Mohs scale, Color: Colorless to white/bluish, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect in two directions, Specific gravity: 2.56-2.59, Adularescence: Blue or white glow
Formation & geological history
Formed from intergrowths of two types of feldspar (orthoclase and albite) that separate into layers as magma cools. When light falls between these layers, it scatters in a phenomenon called adularescence.
Uses & applications
Primarily used as a gemstone in jewelry (rings, pendants, earrings), and valued by crystal collectors and spiritual practitioners.
Geological facts
Ancient Romans theorized that moonstone was formed from frozen beams of moonlight. It is the Florida State Gemstone (commemorating the Apollo moon landings).
Field identification & locations
Identify in the field by its distinct 'shiller' or internal glow when rotated under light. Major deposits are found in Sri Lanka, India, Myanmar, Australia, and Brazil.
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Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock
![Biotite Schist (Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]) — metamorphic](https://media.rock.id/9ca564b5-bc87-402b-965a-69b21f9aa6bf-thumbnail.jpg)
Biotite Schist
Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]
metamorphic