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. Streak: pale green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: 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 to translucent
- Crystal system
- Triclinic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Educational
- Host rock
- As sublimates on basaltic scoria near a volcanic fumarole (>350-400 °C.)
Where rockhounds find cryptochalcite
Classic worldwide localities
- Yadovitaya and Arsenatnaya fumaroles, Second scoria cone, Tolbachik volcano, Kamchatka Peninsula, Russia
Field-hunting tip
Where it forms: As sublimates on basaltic scoria near a volcanic fumarole (>350-400 °C.). If you start seeing cesiodymite, euchlorine, chalcocyanite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cryptochalcite?+
Where is cryptochalcite found?+
Is cryptochalcite safe to handle?+
What rocks look like cryptochalcite?+
What minerals are found with cryptochalcite?+
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What is cryptochalcite used for?+
Find cryptochalcite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
