Wulffite is an exceptionally rare copper-potassium sulfate mineral known primarily from the fumaroles of the Tolbachik volcano in Russia. It typically appears as bright green tabular crystals associated with other complex sulfate minerals in volcanic settings. Because of its extreme rarity and specific formation environment, it is highly sought after by advanced mineral collectors.
Is this wulffite?
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 wulffite with a known reference. Wulffite 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. Streak: light green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark green, deep emerald green, deep bluish green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, crystalline crusts.
Often confused with
Wulffite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Wulffite leaves light green, Krasheninnikovite leaves white.
How to tell apart: Kamchatkite is the harder of the two (Mohs 3.5 vs. 2.5); streak differs, so Wulffite leaves light green, Kamchatkite leaves yellow.
Often found alongside wulffite
Minerals reported to co-occur with wulffite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₃NaCu₄O₂(SO₄)₄
- Mohs hardness
- 2.5
- Density
- 3.23 g/cm³
- Colors
- Streak
- Light green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular crystals, crystalline crusts
- Cleavage
- Perfect, 2 directions parallel to elongation and a third || (010)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As sublimates at a fumarole as incrustations on the surface of basalt scoria or on tenorite or aphthitalite crusts
Where rockhounds find wulffite
Classic worldwide localities
- Arsenatnaya fumarole, Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia
Field-hunting tip
Where it forms: As sublimates at a fumarole as incrustations on the surface of basalt scoria or on tenorite or aphthitalite crusts. If you start seeing euchlorine, fedotovite, hematite in float, you are in the right ground. Typical habit: tabular crystals, crystalline crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify wulffite?+
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Is wulffite safe to handle?+
What rocks look like wulffite?+
What minerals are found with wulffite?+
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Find wulffite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
