Petitjeanite is a rare bismuth phosphate mineral typically found as small, thin, platy crystals in oxidized zones of hydrothermal deposits. Collectors often find it associated with other bismuth minerals in complex pegmatite environments, requiring magnification for detailed observation.
Is this petitjeanite?
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 petitjeanite with a known reference. Petitjeanite 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. Petitjeanite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Petitjeanite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy to prismatic crystals.
Often confused with
Petitjeanite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Petitjeanite and adamantine on Atelestite.
How to tell apart: Petitjeanite is noticeably harder (Mohs 4-5 vs. 2.5); luster reads vitreous on Petitjeanite and adamantine on Preisingerite.
Often found alongside petitjeanite
Minerals reported to co-occur with petitjeanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Bi₃O(OH)(PO₄)₂
- Mohs hardness
- 4-5
- Density
- 5.65 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy to Prismatic Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Bismuth-bearing Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find petitjeanite
Classic worldwide localities
- Kobokobo pegmatite, DR Congo
- Schneeberg, Germany
Field-hunting tip
Look in oxidized bismuth-bearing pegmatites country — that is the host setting where petitjeanite typically forms. If you start seeing atelestite, preisingerite, waylandite in float, you are in the right ground. Field specimens usually show a platy to prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find petitjeanite on the map
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