Chalcanthite is a striking, deep blue secondary mineral typically found in the oxidized zones of copper deposits. It is famous for forming vibrant, crust-like aggregates or delicate, needle-like crystals, though it is highly fragile and readily dissolves in water.
Is this chalcanthite?
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 chalcanthite with a known reference. Chalcanthite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Chalcanthite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Chalcanthite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, blue-green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, massive, stalactitic, fibrous crusts.
Often confused with
Chalcanthite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Azurite is the harder of the two (Mohs 3.5-4 vs. 2.5); streak differs — Chalcanthite leaves white, Azurite leaves light blue; luster reads vitreous on Chalcanthite and vitreous to dull on Azurite.
How to tell apart: Turquoise is the harder of the two (Mohs 5-6 vs. 2.5); luster reads vitreous on Chalcanthite and waxy on Turquoise.
How to tell apart: Antlerite is the harder of the two (Mohs 3.5 vs. 2.5); streak differs — Chalcanthite leaves white, Antlerite leaves light green.
Often found alongside chalcanthite
Minerals reported to co-occur with chalcanthite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuSO₄·5H₂O
- Mohs hardness
- 2.5
- Density
- 2.28 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals, Massive, Stalactitic, Fibrous Crusts
- Cleavage
- Imperfect
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Oxidized Zones of Copper Ore Deposits
- Typical price
- $10-100 per specimen
Where rockhounds find chalcanthite
1 mapped spotsClassic worldwide localities
- Chuquicamata Mine, Chile
- Rio Tinto, Spain
- Bisbee, Arizona, USA
- Mount Isa, Australia
Field-hunting tip
Look in oxidized zones of copper ore deposits country — that is the host setting where chalcanthite typically forms. If you start seeing brochantite, melanterite, cuprite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, stalactitic, fibrous crusts habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Nevada — start trip planning there.
Common questions
How do you identify chalcanthite?+
Where is chalcanthite found?+
Can I find chalcanthite in the United States?+
How much is chalcanthite worth?+
Is chalcanthite safe to handle?+
What rocks look like chalcanthite?+
What minerals are found with chalcanthite?+
What kind of rock does chalcanthite form in?+
What is chalcanthite used for?+
Find chalcanthite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
