Chalcosiderite is a rare copper-iron phosphate mineral that typically forms as attractive, vibrant green to yellow-green crusts or botryoidal coatings. Collectors prize it for its brilliant color, though it is often found in small quantities associated with secondary oxidation zones in copper mines.
Is this chalcosiderite?
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 chalcosiderite with a known reference. Chalcosiderite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white to greenish, pale green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: apple green, dark green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: encrustations.
Often confused with
Chalcosiderite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside chalcosiderite
Minerals reported to co-occur with chalcosiderite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuFe³⁺₆(PO₄)₄(OH)₈·4H₂O
- Mohs hardness
- 4.5
- Density
- 3.22 g/cm³
- Colors
- Streak
- White to greenish, pale green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Encrustations
- Cleavage
- One, perfect; another, less perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare mineral in the oxidized zone of some hydrothermal mineral deposits
Where rockhounds find chalcosiderite
Classic worldwide localities
- Cole and Shattuck mines, Bisbee, Cochise Co., Arizona, USA
- Tyrone mine, Santa Rita, Grant Co., New Mexico, USA
- Mohawk mine, Clark Mountains, San Bernardino Co., California, USA
- King turquoise mine, Conejos Co., Colorado, USA
- West Phoenix United mines, Linkinhorne, and the Gunheath china clay pit, St. Austell, Cornwall, England
- Schneckenstein, and in the Tannenberg mine, Mühlleithen, Saxony, Germany
Field-hunting tip
Where it forms: A rare mineral in the oxidized zone of some hydrothermal mineral deposits. If you start seeing dufrénite, goethite, cyrilovite in float, you are in the right ground. Typical habit: encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify chalcosiderite?+
Where is chalcosiderite found?+
Is chalcosiderite safe to handle?+
What rocks look like chalcosiderite?+
What minerals are found with chalcosiderite?+
What kind of rock does chalcosiderite form in?+
What is chalcosiderite used for?+
Find chalcosiderite on the map
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