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, 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?+
Where is copiapite found?+
Can I find copiapite in the United States?+
How much is copiapite worth?+
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What minerals are found with copiapite?+
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Find copiapite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
