Engelhauptite is a very rare potassium vanadate mineral that occurs as tiny, thin hexagonal plates. It is primarily found in the secondary oxidation zones of vanadium-bearing sandstone deposits, often requiring microscopic study for positive identification.
Is this engelhauptite?
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 engelhauptite with a known reference. Engelhauptite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow-brown, brown with an olive green hue.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: platy crystals.
Often confused with
Engelhauptite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Engelhauptite leaves yellow, Vanadinite leaves white to pale red or pale yellow; luster reads vitreous on Engelhauptite and subresinous to subadamantine on Vanadinite.
How to tell apart: Streak differs, so Engelhauptite leaves yellow, Descloizite leaves orange to brownish red; luster reads vitreous on Engelhauptite and greasy on Descloizite.
Often found alongside engelhauptite
Minerals reported to co-occur with engelhauptite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KCu₃(V₂O₇)(OH)₂Cl
- Mohs hardness
- 2-3
- Density
- 3.86 g/cm³
- Colors
- Yellow-brownBrown with an olive green hue
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
- Crystal habit
- Platy crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late mineral growing in cavities in nepheline basalt
Where rockhounds find engelhauptite
Classic worldwide localities
- Auf’mKopp quarry (Kahlenberg quarry or “Schlackenkegel der Höhe 636 südöstlich Neroth”), Daun, Oberstadtfeld Municipality, Eifel region, Rheinland-Pfalz, Germany
Field-hunting tip
Where it forms: A late mineral growing in cavities in nepheline basalt. If you start seeing volborthite, allophane, malachite in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find engelhauptite on the map
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