Rosièresite is a secondary phosphate mineral typically found as earthy crusts or waxy, botryoidal masses in the oxidized zones of copper and lead mines. It is a rare species that is highly prized by collectors of phosphate minerals due to its often vibrant yellow to brownish-yellow color. It is primarily identified by its distinct association with other secondary copper minerals in hydrothermal veins.
Is this rosièresite?
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 rosièresite with a known reference. Rosièresite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Rosièresite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Rosièresite typically shows a earthy luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown, white.
- 5Look at form & habitCrystal system: amorphous. Typical habit: crusts, reniform, concretionary masses.
Often confused with
Rosièresite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads earthy on Rosièresite and vitreous on Vauxite.
How to tell apart: Turquoise is the harder of the two (Mohs 5-6 vs. 2-3); luster reads earthy on Rosièresite and waxy on Turquoise.
How to tell apart: Luster reads earthy on Rosièresite and vitreous on Wavellite.
Often found alongside rosièresite
Minerals reported to co-occur with rosièresite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Cu,Pb)₃(Al,Fe)₂(PO₄)₄·10H₂O
- Mohs hardness
- 2-3
- Density
- 2.1-2.5 g/cm³
- Streak
- White
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Amorphous
- Crystal habit
- Crusts, Reniform, Concretionary Masses
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Copper and Lead Deposits
- Typical price
- $20-150 for small cabinet specimens
Where rockhounds find rosièresite
Classic worldwide localities
- Rosières, France
- Dravegny, France
- Grube Clara, Germany
Field-hunting tip
Look in oxidized zones of copper and lead deposits country — that is the host setting where rosièresite typically forms. If you start seeing azurite, malachite, limonite in float, you are in the right ground. Field specimens usually show a crusts, reniform, concretionary masses habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find rosièresite on the map
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