Mariposite is a green, chromium-rich variety of muscovite mica found in metamorphic rocks, often associated with gold-bearing quartz veins. It is prized by collectors and lapidary artists for its vibrant green color, typically occurring as massive, foliated, or schistose aggregates.
Is this mariposite?
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 mariposite with a known reference. Mariposite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Mariposite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mariposite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: bright green, emerald green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive.
Often confused with
Mariposite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside mariposite
Minerals reported to co-occur with mariposite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K(Al,Cr)₂(Al,Si)₄O₁₀(OH)₂
- Mohs hardness
- 2.5-3
- Density
- 2.7-3.1 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- Perfect Basal
- Rarity
- Uncommon
- Uses
- Decorative, Lapidary, Collector
- Host rock
- Metamorphic Rocks
- Typical price
- $5-30 for specimens
Where rockhounds find mariposite
1 mapped spotsClassic worldwide localities
- Mariposa County, California, USA
- Mother Lode District, California, USA
- Nevada, USA
Field-hunting tip
Look in metamorphic rocks country — that is the host setting where mariposite typically forms. If you start seeing quartz, ankerite, dolomite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in California — start trip planning there.
Common questions
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Find mariposite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
