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 — that is 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.
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.
