3.0 x 2.0 x 1.0 cm. A rare, complex lead phosphate hydrate that is not well characterized. From a peculiar locality (Huelgoat, Finistère, Brittany, France). Nice thumbnail specimen consisting of small, yellow-brown to grayish, grape-like botryoids. Shows concentric layering on the backside with a radial structure nucleating on sphalerite. This piece may provide good material for further characterization. Eric Asselborn label. Ex. Rock Currier collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Rosièresite
Rosièresite is an IMA-recognized mineral species in the phosphate class, with the chemical formula [Pb,Cu,Al,PO₄,H₂O].
Key properties: specific gravity 2.2; Opaline luster.
IMA symbol Rsr, IMA status: questionable, named in 1841.
Occurs as post-mining incrustations.
It is found associated with Tetrahedrite, cuprite, chrysocolla, malachite, azurite.
The name refers to the mineral’s first occurrence at the Rosières mine, France.