Tsumcorite is a rare zinc-lead arsenate mineral typically found as small, bright yellow to reddish-brown tabular crystals. It is most famous as a type-locality mineral from the Tsumeb Mine in Namibia, where it forms in oxidized polymetallic ore bodies. Collectors should look for its distinctive flattened crystal habit often associated with secondary minerals in the oxidized zones of lead-zinc deposits.
Is this tsumcorite?
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 tsumcorite with a known reference. Tsumcorite 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: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow brown, reddish brown, lemon.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: encrustations, radial, spherical.
Often confused with
Tsumcorite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Tsumcorite is noticeably harder (Mohs 4.5 vs. 3.5); streak differs, so Tsumcorite leaves yellow, Adamite leaves white.
How to tell apart: Streak differs, so Tsumcorite leaves yellow, Legrandite leaves white.
How to tell apart: Streak differs, so Tsumcorite leaves yellow, Mimetite leaves white; luster reads vitreous on Tsumcorite and resinous to subadamantine on Mimetite.
Often found alongside tsumcorite
Minerals reported to co-occur with tsumcorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbZn₂(AsO₄)₂·2H₂O
- Mohs hardness
- 4.5
- Density
- 5.2 g/cm³
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Encrustations, radial, spherical
- Cleavage
- On {001}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of some arsenic-bearing hydrothermal Pb–Zn deposits
Where rockhounds find tsumcorite
Classic worldwide localities
- Richmond-Sitting Bull mine, Galena, Lawrence Co., South Dakota, USA
- Centennial Eureka mine, Tintic district, Juab Co., Utah, USA
- Tsumeb, Namibia
- Thasos, Greece
- Michael mine, Weiler, near Lahr, and the Clara mine, near Oberwolfach, Black Forest, Germany
- Rappold mine and a dump on the Roter Berg, Schneeberg, Saxony, Germany
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of some arsenic-bearing hydrothermal Pb–Zn deposits. If you start seeing willemite, smithsonite, mimetite in float, you are in the right ground. Typical habit: encrustations, radial, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tsumcorite?+
Where is tsumcorite found?+
Is tsumcorite safe to handle?+
What rocks look like tsumcorite?+
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Find tsumcorite on the map
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