Cryptochalcite is a potassium copper sulfate. It was approved as a distinct mineral species in 2015. It was first described from the Yadovitaya and Arsenatnaya fumaroles, Tolbachik volcano, Kamchatka Peninsula, Russia.
Is this cryptochalcite?
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 cryptochalcite with a known reference. Cryptochalcite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Cryptochalcite leaves a pale green streak.
- 3Read the lusterHold the specimen under a strong light. Cryptochalcite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: light green, green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: massive.
Often confused with
Cryptochalcite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cryptochalcite leaves pale green, Aragonite leaves white.
How to tell apart: Streak differs, so Cryptochalcite leaves pale green, Dolomite leaves white.
How to tell apart: Quartz is the harder of the two (Mohs 7 vs. 3); streak differs, so Cryptochalcite leaves pale green, Quartz leaves white.
Often found alongside cryptochalcite
Minerals reported to co-occur with cryptochalcite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Cu₅O(SO₄)₅
- Mohs hardness
- 3
- Density
- 3.411 g/cm³
- Colors
- Streak
- Pale Green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Educational
- Host rock
- Sedimentary
Where rockhounds find cryptochalcite
Classic worldwide localities
- Yadovitaya and Arsenatnaya fumaroles, Kamchatka Peninsula, Russia
Field-hunting tip
Look in sedimentary country, the host setting where cryptochalcite typically forms. If you start seeing calcite, dolomite, quartz in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cryptochalcite?+
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What rocks look like cryptochalcite?+
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Find cryptochalcite on the map
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