Aluminocopiapite is a rare hydrated sulfate mineral that typically forms as yellow efflorescent crusts or powdery aggregates in the oxidation zones of sulfide-rich ore bodies. It is best identified through its association with other secondary sulfate minerals and its distinct, often bright yellow, coloration. Due to its solubility in water, specimens should be stored in a dry, humidity-controlled environment to prevent degradation.
Is this aluminocopiapite?
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 aluminocopiapite with a known reference. Aluminocopiapite 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. Aluminocopiapite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Aluminocopiapite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, pale yellow, golden yellow.
- 5Look at form & habitCrystal system: triclinic. Typical habit: massive, crusts, tabular crystals.
Often confused with
Aluminocopiapite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Aluminocopiapite leaves white, Copiapite leaves yellow.
How to tell apart: Luster reads pearly on Aluminocopiapite and silky on Fibroferrite.
How to tell apart: Luster reads pearly on Aluminocopiapite and vitreous on Halotrichite.
Often found alongside aluminocopiapite
Minerals reported to co-occur with aluminocopiapite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AlFe₄(SO₄)₆(OH)₂·20H₂O
- Mohs hardness
- 2.5-3
- Density
- 2.2-2.3 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Massive, Crusts, Tabular Crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Sulfide Ore Deposits
- Typical price
- $20-100 per specimen depending on size
Where rockhounds find aluminocopiapite
Classic worldwide localities
- Chile
- United States
- Russia
- Argentina
Field-hunting tip
Look in oxidized zones of sulfide ore deposits country — that is the host setting where aluminocopiapite typically forms. If you start seeing copiapite, jarosite, gypsum in float, you are in the right ground. Field specimens usually show a massive, crusts, tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify aluminocopiapite?+
Where is aluminocopiapite found?+
How much is aluminocopiapite worth?+
What rocks look like aluminocopiapite?+
What minerals are found with aluminocopiapite?+
What kind of rock does aluminocopiapite form in?+
What is aluminocopiapite used for?+
Find aluminocopiapite on the map
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