Otjisumeite is an extremely rare lead-germanium oxide found almost exclusively in the Tsumeb Mine in Namibia. Collectors prize its distinct pale yellow tabular crystal form, which typically occurs in association with complex sulfide ores.
Is this otjisumeite?
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 otjisumeite with a known reference. Otjisumeite sits at Mohs ~3, 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: greasy to subadamantine.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: pseudo hexagonal.
Often confused with
Otjisumeite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads greasy to subadamantine on Otjisumeite and adamantine, resinous to vitreous on Anglesite.
How to tell apart: Luster reads greasy to subadamantine on Otjisumeite and adamantine, tending toward vitreous, resinous on Cerussite.
Often found alongside otjisumeite
Minerals reported to co-occur with otjisumeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbGe₄O₉
- Mohs hardness
- ~3
- Density
- 5.77 g/cm³
- Streak
- White
- Luster
- Greasy to subadamantine
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Pseudo hexagonal
- Cleavage
- {001}, interrupted
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In cavities in oxidized germanium-bearing sulfides in a dolostone-hosted hydrothermal polymetallic ore deposit
Where rockhounds find otjisumeite
Classic worldwide localities
- Tsumeb, Namibia
Field-hunting tip
Where it forms: In cavities in oxidized germanium-bearing sulfides in a dolostone-hosted hydrothermal polymetallic ore deposit. If you start seeing tennantite, germanite, reniérite in float, you are in the right ground. Typical habit: pseudo hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify otjisumeite?+
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What rocks look like otjisumeite?+
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Find otjisumeite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
