Colemanite

Colemanite - of interest to jewellers as the principal source of borax until the 1930s, it is also cut and faceted for collectors. Crystals can be clear or red, with natural fluorescence.

Named after William Tell Coleman, a pioneer of the borax industry who owned the Harmony Borax Works in Death Valley USA where it was discovered in 1882.

Although rarely used for adornment there are cut stones available.