Ferricopiapite is a secondary sulfate mineral that typically forms as yellow, earthy to crystalline crusts in the oxidation zones of sulfide-rich ore bodies. It is famously associated with the breakdown of pyrite and other iron-sulfide minerals in arid environments where evaporation leads to the precipitation of hydrated sulfates.
Is this ferricopiapite?
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 ferricopiapite with a known reference. Ferricopiapite 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. Ferricopiapite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Ferricopiapite 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: platy crystals, tabular, crusts, efflorescent aggregates.
Often confused with
Ferricopiapite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads pearly on Ferricopiapite and vitreous on Jarosite.
How to tell apart: Streak differs, so Ferricopiapite leaves yellow, Melanterite leaves white; luster reads pearly on Ferricopiapite and vitreous on Melanterite.
Often found alongside ferricopiapite
Minerals reported to co-occur with ferricopiapite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe³⁺₄(SO₄)₆(OH)₂·20H₂O
- Mohs hardness
- 2.5-3
- Density
- 2.1-2.2 g/cm³
- Streak
- Yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Platy Crystals, Tabular, Crusts, Efflorescent Aggregates
- Cleavage
- Perfect On {010}
- Rarity
- Common
- Uses
- Collector
- Host rock
- Oxidized Zones of Sulfide Ore Deposits
- Typical price
- $10-50 per specimen
Where rockhounds find ferricopiapite
Classic worldwide localities
- Chile
- Spain
- USA (California, Arizona)
- Germany
Field-hunting tip
Look in oxidized zones of sulfide ore deposits country, the host setting where ferricopiapite typically forms. If you start seeing jarosite, melanterite, gypsum in float, you are in the right ground. Field specimens usually show a platy crystals, tabular, crusts, efflorescent aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferricopiapite?+
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How much is ferricopiapite worth?+
What rocks look like ferricopiapite?+
What minerals are found with ferricopiapite?+
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Find ferricopiapite on the map
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