Where is Moonstone found?
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, particularly from the mines near Meetiyagoda.
India
Produces a significant amount of moonstone, often with a more yellowish or brownish body color and a white or rainbow sheen.
Myanmar (Burma)
Known for producing fine moonstone, often with a strong blue adularescence.
Madagascar
A source of various colors of moonstone, including white, gray, and peach.
Tanzania
Produces moonstone, sometimes with a greenish tint.
Brazil
Known for some occurrences of moonstone.
United States (e.g., New Mexico, Virginia, Pennsylvania)
Localities exist, but generally not commercial-grade gemstone material. Often found in pegmatites.
Collecting tips
- Look for Feldspar-Rich Rocks. Moonstone is a variety of feldspar, so search in geological environments known for feldspar-rich igneous rocks (granites, syenites, pegmatites) and certain metamorphic rocks.
- Identify Adularescence. The most distinctive feature is the adularescence. Rotate potential specimens under a light source to observe the characteristic shimmering, billowy light effect. This is best seen on smooth, rounded surfaces or cleavage planes.
- Check for Cleavage. Feldspars exhibit two perfect cleavage directions at or near 90 degrees. Look for these flat, reflective surfaces on broken specimens.
- Consider Luster and Hardness. Moonstone has a vitreous to pearly luster. Its hardness (6-6.5 on Mohs scale) means it can scratch glass but can be scratched by quartz.
- Examine for Inclusions. Some moonstones may contain fine needle-like inclusions of rutile or other minerals, which can sometimes enhance the adularescence or create a cat's eye effect (chatoyancy).
Quick Check
- Color:
- Colorless to white, with a characteristic blue or white sheen (adularescence).
- Luster:
- Vitreous to pearly.
- Streak:
- White.
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