Blue Moonstone is a variety of adularia feldspar prized for its ethereal blue schiller, also known as adularescence, caused by light scattering between alternating thin layers of orthoclase and albite. Collectors should look for a strong, centered blue sheen that moves across the surface as the stone is tilted. It is most commonly found in igneous pegmatites and is a popular choice for high-end cabochon jewelry.
Is this blue 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 blue moonstone with a known reference. Blue Moonstone sits at Mohs 6-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Blue Moonstone leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Blue Moonstone typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, massive, granular.
Often confused with
Blue Moonstone vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside blue moonstone
Minerals reported to co-occur with blue 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
- 6-6.5
- Density
- 2.56-2.62 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive, Granular
- Cleavage
- Perfect Basal and Clinopinacoidal
- Rarity
- Common
- Uses
- Gemstone, Lapidary, Collector
- Host rock
- Pegmatites, Hydrothermal Veins
- Typical price
- $10-50 per carat for average stones, higher for intense blue adularescence
Where rockhounds find blue moonstone
1 mapped spotsClassic worldwide localities
- Sri Lanka
- India
- Myanmar
- Madagascar
- Tanzania
Field-hunting tip
Look in pegmatites, hydrothermal veins country, the host setting where blue moonstone typically forms. If you start seeing quartz, tourmaline, microcline in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Virginia. Start trip planning there.
More blue moonstone photos
Common questions
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Find blue moonstone on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
