Moonstone is a variety of the feldspar group known for its distinctive adularescence, a floating, billowy light effect caused by light scattering between thin, alternating layers of orthoclase and albite. Collectors should look for specimens that exhibit a bright, centered blue sheen against a clear, colorless base, commonly found in pegmatite deposits.
Is this moonstone?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch moonstone with a known reference. Moonstone sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Moonstone leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Moonstone typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, blue, peach, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Moonstone vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside moonstone
Minerals reported to co-occur with moonstone. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KAlSi₃O₈
- Mohs hardness
- 6
- Density
- 2.55-2.63 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect
- Rarity
- Common
- Uses
- Gemstone, Lapidary, Collector
- Host rock
- Pegmatites, Granites, And Hydrothermal Veins
- Typical price
- $5-50 for small cabochons, $100-500+ for premium blue adularescence specimens
Where rockhounds find moonstone
29 mapped spotsClassic worldwide localities
- Sri Lanka
- India
- Madagascar
- Myanmar
- USA
U.S. states with moonstone
Each link opens a state-specific list of mapped rockhounding spots that produce moonstone.
Field-hunting tip
Look in pegmatites, granites, and hydrothermal veins country — that is the host setting where moonstone typically forms. If you start seeing quartz, muscovite, tourmaline in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Oregon, North Carolina, California — start trip planning there.
Common questions
How do you identify moonstone?+
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Can I find moonstone in the United States?+
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Find moonstone on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
