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 — 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 — that is 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?+
Where is ferricopiapite found?+
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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