Borax altered to Tincalconite

Item Description

Outstanding single crystal of Borax from the famous U.S. Borax Mine in California, that has altered to the mineral tincalconite. The white color comes from a slow alteration to Tincalconite as the Borax naturally dewaters. The sharp form and sheer size of this crystal, as well as its superb termination, make this one of the best condition in single Borax crystals I have seen in awhile as they are fairly uncommon survivors on the market today. These are fascinating and the surface is soft and chalky, but solid. From the extensive collection of Bob Reynolds, who cherished both minerals and fossils as he collected. Bob is a prolific author and has had several curating positions in museums.