Cuprocopiapite is a rare copper-bearing member of the copiapite group formed by the oxidation of iron and copper sulfide minerals. It typically presents as yellow to greenish-yellow crusts or small, platy crystal aggregates in arid mining environments. Collectors should be aware that like other hydrous sulfates, it is water-soluble and should be stored in a dry environment.

Hardness

2.5

Mohs

Luster

Pearly

Streak

Light yellow

Transparency

Semitransparent

mineralrareCopiapite Group family

Cuprocopiapite

Hardness: 2.5
Luster: Pearly
Streak: Light yellow
Transparency: Semitransparent

Is this cuprocopiapite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch cuprocopiapite with a known reference. Cuprocopiapite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: light yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: pearly.
4
Match the color range
Compare against the expected color range: yellow, greenish yellow, orange.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals, granular crusts, powdery efflorescences.

Often confused with

Cuprocopiapite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Copiapite

Mohs 2.5-3

How to tell apart: Streak differs, so Cuprocopiapite leaves light yellow, Copiapite leaves pale yellow.

How to tell apart: Streak differs, so Cuprocopiapite leaves light yellow, Fibroferrite leaves white.

How to tell apart: Cuprocopiapite is noticeably harder (Mohs 2.5 vs. 1.5); streak differs, so Cuprocopiapite leaves light yellow, Halotrichite leaves white; luster reads pearly on Cuprocopiapite and vitreous on Halotrichite.

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Often found alongside cuprocopiapite

Minerals reported to co-occur with cuprocopiapite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CuFe₄(SO₄)₆(OH)₂·20H₂O
Mohs hardness: 2.5
Density: 2.23 g/cm³
Colors: Yellow Greenish yellow Orange
Streak: Light yellow
Luster: Pearly
Transparency: Semitransparent
Crystal system: Triclinic
Crystal habit: Platy crystals, granular crusts, powdery efflorescences
Cleavage: 010, perfect; 101 imperfect (by analogy with copiapite)
Rarity: Rare
Uses: Collector
Host rock: A rare secondary mineral probably formed by reaction between copiapite and copper sulfate-bearing solutions, preserved in arid climates

Where rockhounds find cuprocopiapite

Classic worldwide localities

Chuquicamata and at Quetena, west of Calama, Antofagasta, Chile

Field-hunting tip

Where it forms: A rare secondary mineral probably formed by reaction between copiapite and copper sulfate-bearing solutions, preserved in arid climates. If you start seeing copiapite, parabutlerite, chalcanthite in float, you are in the right ground. Typical habit: platy crystals, granular crusts, powdery efflorescences. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cuprocopiapite?+

Mohs hardness is 2.5. Luster: pearly. The streak is light yellow. Common colors include yellow, greenish yellow, orange.

Where is cuprocopiapite found?+

Notable localities include Chuquicamata and at Quetena, west of Calama, Antofagasta, Chile.

Is cuprocopiapite safe to handle?+

Cuprocopiapite contains copper. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like cuprocopiapite?+

Cuprocopiapite is most often confused with Copiapite, Fibroferrite, Halotrichite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with cuprocopiapite?+

Cuprocopiapite commonly co-occurs with Copiapite, Parabutlerite, Chalcanthite, Jarosite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cuprocopiapite form in?+

Where it forms: A rare secondary mineral probably formed by reaction between copiapite and copper sulfate-bearing solutions, preserved in arid climates. Working float back to the host body is the standard way to chase a fresh occurrence.

What is cuprocopiapite used for?+

Cuprocopiapite is used in collector.

Find cuprocopiapite on the map

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