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 3-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Lukrahnite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Lukrahnite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-green, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed crystals, radial aggregates, crusts.
Often confused with
Lukrahnite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Lukrahnite leaves yellow, Tsumcorite leaves yellowish.
How to tell apart: Streak differs — Lukrahnite leaves yellow, Arseniosiderite leaves yellowish-brown; luster reads vitreous on Lukrahnite and 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
- CaCu(AsO₄)(AsO₃OH)
- Mohs hardness
- 3-4
- Density
- 4.67 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Bladed Crystals, Radial Aggregates, Crusts
- Cleavage
- Distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Mineral Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find lukrahnite
Classic worldwide localities
- Tsumeb Mine, Namibia
- Guanaco, Chile
Field-hunting tip
Look in hydrothermal mineral deposits country — that is the host setting where lukrahnite typically forms. If you start seeing tsumcorite, wulfenite, dolomite in float, you are in the right ground. Field specimens usually show a bladed crystals, radial aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find lukrahnite on the map
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