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, 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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