Where is Moonstone found?
Adularia (a variety of Orthoclase Feldspar)
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Open the appMoonstone occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Moonstone
Sri Lanka
Historically the primary source of high-quality blue moonstone, found in pegmatites and alluvial deposits.
India
Produces a significant amount of moonstone, often with a more brownish or yellowish body color and a less intense adularescence.
Myanmar (Burma)
Known for producing fine moonstone, often with a good blue sheen.
Madagascar
A source of various feldspar minerals, including moonstone.
Tanzania
Produces moonstone with a range of body colors and adularescence.
Brazil
Some occurrences of moonstone have been reported.
United States (e.g., New Mexico, Virginia)
Minor occurrences of moonstone have been found in various states.
Switzerland (Adula Alps)
The type locality for adularia, where it is found in alpine-type fissures.
Collecting tips
- Look for Adularescence. The most distinctive feature of moonstone is its adularescence. Rotate the specimen under a light source to observe the characteristic shimmering, milky, bluish-white glow that appears to float just beneath the surface.
- Check for Cleavage. Feldspars, including moonstone, exhibit perfect cleavage in two directions at nearly 90 degrees. This can be observed as flat, reflective surfaces when the mineral breaks.
- Consider the Geological Environment. Search in areas known for pegmatites, hydrothermal veins, or alpine-type fissures. Alluvial deposits downstream from such primary sources can also yield moonstone.
- Hardness Test (with caution). Moonstone has a Mohs hardness of 6-6.5. It can scratch glass but can be scratched by quartz. Use this test carefully to avoid damaging the specimen.
- Distinguish from Similar Minerals. Be aware of similar-looking minerals like labradorite (which exhibits labradorescence, a broader play of colors) and opal (which has opalescence, a distinct internal play of spectral colors). True moonstone's adularescence is typically a bluish-white sheen.
Quick Check
- Color:
- Colorless to white, gray, brown, yellow, orange, green, pink, with a bluish-white adularescence.
- Luster:
- Vitreous to pearly, with adularescence.
- Streak:
- White
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