Thometzekite is a rare copper-lead arsenate mineral most famously found in the oxidation zones of the Tsumeb Mine in Namibia. It typically occurs as small, vibrant green crusts or clusters of minute crystals that can be difficult to distinguish from related arsenate minerals without chemical analysis.
Is this thometzekite?
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 thometzekite with a known reference. Thometzekite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Thometzekite leaves a pale yellow-green streak.
- 3Read the lusterHold the specimen under a strong light. Thometzekite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crusts, druzy, micro-crystals.
Often confused with
Thometzekite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Conichalcite is the harder of the two (Mohs 4.5 vs. 3.5); streak differs — Thometzekite leaves pale yellow-green, Conichalcite leaves light green.
How to tell apart: Streak differs — Thometzekite leaves pale yellow-green, Duftite leaves light green.
How to tell apart: Streak differs — Thometzekite leaves pale yellow-green, Austinite leaves white.
Often found alongside thometzekite
Minerals reported to co-occur with thometzekite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbCu₂(AsO₄)₂·2H₂O
- Mohs hardness
- 3.5
- Density
- 6.05 g/cm³
- Colors
- Streak
- Pale Yellow-green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Crusts, Druzy, Micro-crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Hydrothermal Lead-zinc Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find thometzekite
Classic worldwide localities
- Tsumeb Mine, Namibia
- Guanaco, Chile
- Mapimi, Mexico
Field-hunting tip
Look in oxidized hydrothermal lead-zinc deposits country — that is the host setting where thometzekite typically forms. If you start seeing tsumcorite, mimetite, smithsonite in float, you are in the right ground. Field specimens usually show a crusts, druzy, micro-crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find thometzekite on the map
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