Demesmaekerite is a rare secondary mineral typically found as small, vibrant honey-yellow needles or blades. It is known primarily from the uranium-rich oxidation zones of the Katanga copper belt in the Democratic Republic of the Congo.
Is this demesmaekerite?
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 demesmaekerite with a known reference. Demesmaekerite 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. Demesmaekerite leaves a yellowish streak.
- 3Read the lusterHold the specimen under a strong light. Demesmaekerite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: honey-yellow, brownish-yellow, greenish-yellow.
- 5Look at form & habitCrystal system: triclinic. Typical habit: acicular or bladed crystals, radiating aggregates.
Often confused with
Demesmaekerite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Demesmaekerite is noticeably harder (Mohs 3 vs. 2); streak differs — Demesmaekerite leaves yellowish, Guilleminite leaves yellow.
How to tell apart: Derbylite is the harder of the two (Mohs 5 vs. 3); streak differs — Demesmaekerite leaves yellowish, Derbylite leaves brown; luster reads vitreous on Demesmaekerite and submetallic on Derbylite.
Often found alongside demesmaekerite
Minerals reported to co-occur with demesmaekerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂Cu₅(SeO₃)₆(OH)₆·2H₂O
- Mohs hardness
- 3
- Density
- 4.57 g/cm³
- Streak
- Yellowish
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Acicular or Bladed Crystals, Radiating Aggregates
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Uranium-copper Deposits
- Typical price
- $100-500 for small thumbnail specimens
Where rockhounds find demesmaekerite
Classic worldwide localities
- Musonoi Mine, Democratic Republic of the Congo
- Shinkolobwe Mine, Democratic Republic of the Congo
Field-hunting tip
Look in oxidized uranium-copper deposits country — that is the host setting where demesmaekerite typically forms. If you start seeing guilleminite, marthozite, malachite in float, you are in the right ground. Field specimens usually show a acicular or bladed crystals, radiating aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find demesmaekerite on the map
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