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 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: earthy.
- 4Match the color rangeCompare against the expected color range: green, bluish green.
- 5Look at form & habitCrystal system: monoclinic. 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: Streak differs, so Thometzekite leaves white, Conichalcite leaves green; luster reads earthy on Thometzekite and vitreous to somewhat greasy on Conichalcite.
How to tell apart: Streak differs, so Thometzekite leaves white, Duftite leaves pale green to white; luster reads earthy on Thometzekite and dull to vitreous on fractures on Duftite.
How to tell apart: Luster reads earthy on Thometzekite and subadamantine to silky in aggregates on Austinite.
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
- 4.5
- Density
- 5.21 g/cm³
- Colors
- Streak
- White
- Luster
- Earthy
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Crusts, druzy, micro-crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare secondary mineral from an oxidized zone in a dolostone-hosted hydrothermal polymetallic ore deposit (Tsumeb, Namibia)
Where rockhounds find thometzekite
Classic worldwide localities
- Gold Hill, Tooele Co., Utah, USA
- Tsumeb, Namibia
- Moldava, 20 km northwest of Teplice, Czech Republic
- Clara mine, near Oberwolfach, Black Forest, Germany
- Broken Hill, New South Wales, Australia
Field-hunting tip
Where it forms: A very rare secondary mineral from an oxidized zone in a dolostone-hosted hydrothermal polymetallic ore deposit (Tsumeb, Namibia). If you start seeing anglesite, mimetite, gypsum in float, you are in the right ground. Typical habit: crusts, druzy, micro-crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify thometzekite?+
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Find thometzekite on the map
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