Copiapite is a secondary sulfate mineral commonly found as a bright yellow efflorescence in the oxidized zones of pyrite-rich ore deposits. Collectors primarily find it as thin crusts, aggregates of small platy crystals, or powdery masses associated with other secondary iron sulfates.
Is this copiapite?
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 copiapite with a known reference. Copiapite 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. Copiapite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Copiapite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, golden yellow, orange yellow.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, massive, botryoidal, crusts, efflorescences.
Often confused with
Copiapite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside copiapite
Minerals reported to co-occur with copiapite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺Fe³⁺₄(SO₄)₆(OH)₂·20H₂O
- Mohs hardness
- 2.5-3
- Density
- 2.1 g/cm³
- Streak
- Yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals, Massive, Botryoidal, Crusts, Efflorescences
- Cleavage
- Good
- Rarity
- Common
- Uses
- Collector, Scientific Study
- Host rock
- Oxidized Zones of Sulfide Ore Deposits
- Typical price
- $10-60 for small cabinet specimens
Where rockhounds find copiapite
1 mapped spotsClassic worldwide localities
- Chile
- Spain
- USA (Arizona)
- Germany
- Czech Republic
Field-hunting tip
Look in oxidized zones of sulfide ore deposits country — that is the host setting where copiapite typically forms. If you start seeing pyrite, melanterite, coquimbite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, botryoidal, crusts, efflorescences habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Missouri — start trip planning there.
Common questions
How do you identify copiapite?+
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Can I find copiapite in the United States?+
How much is copiapite worth?+
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Find copiapite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
