Boleite: Gemstone Information

Boléite forms deep Prussian blue to indigo cubic crystals which are often surficially overlaid with or overgrown by pseudoboleite. The hardness is 3–3.5, the SG 5.05 and there is one direction of perfect cleavage. The RI is 2.05. Boléite occurs as a secondary mineral formed by the reaction of chloride with primary sulphides in the oxidized zone of lead–copper deposits. Facetable material will almost certainly have come from the Amelia mine, Boleo, Santa Rosalia, Baja California, Mexico. The composition is KPb26Ag9Cu24Cl62(OH)48.