CUBANITE (miniature)- BARRACANITE

Cubanite is a copper iron sulfide mineral, typically found as a minor alteration mineral within magmatic sulfide deposits. Its chemical formula is CuFe2S3, and it exhibits a bronze to brass-yellow coloration. On the Mohs hardness scale, cubanite ranks between 3.5 and 4 and possesses an orthorhombic crystal system. While chemically akin to chalcopyrite, cubanite is less prevalent due to its specific crystallization requirements. It is primarily found in high-temperature hydrothermal mineral deposits, often associated with pyrrhotite and pentlandite, and forms through the exsolution process from chalcopyrite at temperatures ranging from 200 to 210 °C. If subjected to temperatures exceeding 210 °C, cubanite converts to isocubanite, losing its magnetic properties and orthorhombic structure in the process. This transformation is irreversible upon cooling. Cubanite has also been detected in chondrites and dust grain samples, enhancing the accuracy of copper isotope analysis.

The name "cubanite" derives from the Spanish term "Cubano," meaning Cuban, combined with the suffix "-ite," commonly used for minerals. It was first identified in 1843 in the Mayarí-Baracoa Belt of Holguín Province, Cuba, and is occasionally referred to as barracanite in certain literature.