Lukrahnite is a rare calcium-copper arsenate mineral first identified in the world-famous Tsumeb mine. It typically occurs as small, delicate bladed crystals or radial sprays within oxidized zones of arsenic-rich base metal deposits.
Is this lukrahnite?
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 lukrahnite with a known reference. Lukrahnite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: dull for aggregates to subadamantine on fracture surfaces.
- 4Match the color rangeCompare against the expected color range: yellow.
- 5Look at form & habitCrystal system: triclinic. Typical habit: aggregates, microscopic crystals, spherical.
Often confused with
Lukrahnite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Lukrahnite leaves light yellow, Tsumcorite leaves yellow; luster reads dull for aggregates to subadamantine on fracture surfaces on Lukrahnite and vitreous on Tsumcorite.
How to tell apart: Streak differs, so Lukrahnite leaves light yellow, Arseniosiderite leaves ocher-yellow; luster reads dull for aggregates to subadamantine on fracture surfaces on Lukrahnite and submetallic to silky on Arseniosiderite.
Often found alongside lukrahnite
Minerals reported to co-occur with lukrahnite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCuFe(AsO₄)₂(OH,H₂O)₂
- Mohs hardness
- 5
- Density
- 4.18 g/cm³
- Colors
- Streak
- Light yellow
- Luster
- Dull for aggregates to subadamantine on fracture surfaces
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Aggregates, microscopic crystals, spherical
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Secondary in the oxidation zone of polymetallic sulfarsenide deposits
Where rockhounds find lukrahnite
Classic worldwide localities
- Tsumeb mine, Namibia
- Pucher shaft, Schneeberg, Saxony, Germany
Field-hunting tip
Where it forms: Secondary in the oxidation zone of polymetallic sulfarsenide deposits. If you start seeing beudantite, adamite, conichalcite in float, you are in the right ground. Typical habit: aggregates, microscopic crystals, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify lukrahnite?+
Where is lukrahnite found?+
Is lukrahnite safe to handle?+
What rocks look like lukrahnite?+
What minerals are found with lukrahnite?+
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Find lukrahnite on the map
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