Detailed information
Dimensions
83 x 58 x 23
mm
Locality
Baccu Locci Mine Villaputzu, Cagliari Province Sardinia, Italy
Condition
No recorded repairs
This is a very large (for the species) and extremely rich crystallized specimen of Chalcomenite from arguably its best-known occurrence, at Baccu Locci mine in Sardinia. Not the Type Locality - which was published about in 1881 from Cerro de Cacheuta, Cacheuta District, Luján de Cuyo department, Mendoza Province, Argentina - the finds at Baccu Locci mine are shrouded in mystery. Small-scale mining for lead and zinc were known in the area around the mine during the 19th century with more substantial attempts to mine commencing in the latest years of the 19th century. The mine was never particularly successful, with problems with ore processing and health and safety issues. Its peak year for employment was 1952 but, as with all Sardinian mines, a decline set in, and by 1965 it was closed. The first record of Chalcomenite from there was published in 1989, but its is likely that the specimens were known about while the mine was active. With bright blue, highly lustrous crystal sprays measuring to over 1 cm on a grey-black matrix this is an extremely fine display quality example of this very rare copper selenite hydrate species. Several other less conspicuous secondary selenium-bearing species have since been described from this mine as new species, but Chalcomenite is the most prominent for its appearance. Under magnification the crystals of Chalcomenite are seen to form feathery divergent sprays typically within areas of white in the weathered sulphide matrix. Ex Professor Werner Paar Collection, this is a world-class example of this extremely rare, yet colourful species.
