Boleite is an extremely rare lead-copper-silver chloride hydroxide forming sharp deep-blue pseudocubic crystals. The species is essentially restricted to the Boleo copper-cobalt district in Baja California Sur, Mexico — its type locality.
Properties
- Formula: KPb26Ag9Cu24Cl62(OH)48
- Crystal system: Tetragonal (pseudocubic)
- Hardness: 3 – 3.5
- Color: Deep Prussian-blue to indigo
- Streak: Pale blue
- Luster: Vitreous to pearly
- Cleavage: Perfect on {001} and {100}
- Density: 5.0 – 5.1 g/cm³
Occurrence
Type and primary locality: Amelia and Cumengeite mines, Boleo, Santa Rosalía (Baja California Sur, Mexico). Extremely rare elsewhere — a few crystals from Broken Hill (Australia) and Caracoles (Chile). Often intergrown or epitaxial with cumengeite and pseudoboleite.
Identification
Sharp pseudocubic deep-blue crystals + Mexican pedigree + epitaxial overgrowths of cumengeite. The crystals are pseudocubic but actually tetragonal — verifying optical properties is decisive.
Collector Notes
One of the rarest collector minerals — sharp boleite cubes on matrix command four-figure prices for thumbnails. The Boleo district is depleted; specimens are essentially unrenewable supply.
Found at these Localities
- Boleo District (Santa Rosalía) (圣罗萨利亚博莱奥铜矿区)
- Broken Hill (布罗肯希尔铅锌银矿)
