Grootfonteinite is a rare lead carbonate mineral originally described from the lead-rich deposits near Grootfontein, Namibia. It typically occurs as small, clear, rhombohedral crystals associated with other secondary lead minerals in oxidized ore zones.
Is this grootfonteinite?
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 grootfonteinite with a known reference. Grootfonteinite sits at Mohs ~2, 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: adamantine.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: rhombohedral crystals.
Often confused with
Grootfonteinite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside grootfonteinite
Minerals reported to co-occur with grootfonteinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₃O(CO₃)₂
- Mohs hardness
- ~2
- Density
- 6.856 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Rhombohedral crystals
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A product of the regional metamorphism of a Pb-Mn-(As-Ba)-rich, chemically heterogeneous, volcanic-hydrothermal assemblage
Where rockhounds find grootfonteinite
Classic worldwide localities
- Kombat mine, Grootfontein district, Otjozondjupa region, northern Namibia
Field-hunting tip
Where it forms: A product of the regional metamorphism of a Pb-Mn-(As-Ba)-rich, chemically heterogeneous, volcanic-hydrothermal assemblage. If you start seeing jacobsite, cerussite, dolomite in float, you are in the right ground. Typical habit: rhombohedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify grootfonteinite?+
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What rocks look like grootfonteinite?+
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Find grootfonteinite on the map
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