Bartelkeite is a rare lead-iron-germanium oxide mineral found almost exclusively in the Tsumeb mine in Namibia. It typically occurs as minute, clear to white tabular crystals associated with other rare germanium minerals. Due to its extreme scarcity, it is a highly prized species for advanced mineral collectors.
Is this bartelkeite?
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 bartelkeite with a known reference. Bartelkeite sits at Mohs ~4, 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: subadamantine.
- 4Match the color rangeCompare against the expected color range: colorless, light green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, tabular.
Often confused with
Bartelkeite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Bartelkeite is noticeably harder (Mohs ~4 vs. 2.5-3); luster reads subadamantine on Bartelkeite and adamantine, resinous to vitreous on Anglesite.
How to tell apart: Luster reads subadamantine on Bartelkeite and adamantine, tending toward vitreous, resinous on Cerussite.
Often found alongside bartelkeite
Minerals reported to co-occur with bartelkeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbFeGe(Ge₂O₇)(OH)₂·H₂O
- Mohs hardness
- ~4
- Density
- 4.97 g/cm³
- Colors
- Streak
- White
- Luster
- Subadamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, tabular
- Cleavage
- {101}, distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare mineral in cavities in oxidized primary germanium ore from a dolostone-hosted hydrothermal polymetallic ore deposit
Where rockhounds find bartelkeite
Classic worldwide localities
- Tsumeb, Namibia
Field-hunting tip
Where it forms: A very rare mineral in cavities in oxidized primary germanium ore from a dolostone-hosted hydrothermal polymetallic ore deposit. If you start seeing germanite, reniérite, tennantite in float, you are in the right ground. Typical habit: acicular, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find bartelkeite on the map
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