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 3-3.5, 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: opaline.
- 4Match the color rangeCompare against the expected color range: yellow, pale brown.
- 5Look at form & habitCrystal system: amorphous. Typical habit: stalactitic.
Often confused with
Rosièresite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads opaline on Rosièresite and vitreous on Vauxite.
How to tell apart: Turquoise is the harder of the two (Mohs 5-6 vs. 3-3.5); luster reads opaline on Rosièresite and vitreous in crystals; dull to waxy if massive on Turquoise.
How to tell apart: Luster reads opaline on Rosièresite and vitreous to resinous, pearly 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
- PbxCuyAlz(PO₄)m·nH₂O
- Mohs hardness
- 3-3.5
- Density
- 2.2 g/cm³
- Colors
- Streak
- White
- Luster
- Opaline
- Transparency
- Semitransparent
- Crystal system
- Amorphous
- Crystal habit
- Stalactitic
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As post-mining incrustations
Where rockhounds find rosièresite
Classic worldwide localities
- Rosières copper mine, about one km east of Carmaux, Tarn, France
Field-hunting tip
Where it forms: As post-mining incrustations. If you start seeing tetrahedrite, cuprite, chrysocolla in float, you are in the right ground. Typical habit: stalactitic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify rosièresite?+
Where is rosièresite found?+
Is rosièresite safe to handle?+
What rocks look like rosièresite?+
What minerals are found with rosièresite?+
What kind of rock does rosièresite form in?+
What is rosièresite used for?+
Find rosièresite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
