Damourite is a fine-grained, hydrous, micaceous variety of muscovite that typically forms as an alteration product of minerals like kyanite or corundum. It usually appears as dense, silky, or pearly masses or scaly aggregates rather than distinct crystals. Collectors often find it associated with metamorphic terrains and altered pegmatite zones.
Is this damourite?
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 damourite with a known reference. Damourite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Damourite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Damourite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: white, yellowish-white, pale green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, micaceous aggregates, scaly.
Often confused with
Damourite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside damourite
Minerals reported to co-occur with damourite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KAl₂(AlSi₃O₁₀)(OH)₂
- Mohs hardness
- 2-3
- Density
- 2.7-3.0 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive, Micaceous Aggregates, Scaly
- Cleavage
- Perfect Basal
- Rarity
- Common
- Uses
- Collector
- Host rock
- Metamorphic Rocks, Alteration Zones of Pegmatites
- Typical price
- $5-30 for small mineral specimens
Where rockhounds find damourite
2 mapped spotsClassic worldwide localities
- Pontorson, France
- St. Gotthard, Switzerland
- Chester, Massachusetts, USA
- Custer, South Dakota, USA
Field-hunting tip
Look in metamorphic rocks, alteration zones of pegmatites country — that is the host setting where damourite typically forms. If you start seeing kyanite, corundum, topaz in float, you are in the right ground. Field specimens usually show a massive, micaceous aggregates, scaly habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in North Carolina — start trip planning there.
Common questions
How do you identify damourite?+
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Find damourite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
