An exceptional thumbnail of this exceedingly rare silver tin sulfide from Colquechaca, Bolivia, the type locality! This little jewel of an oddity consists of well-formed to mal-formed, steel-gray crystals of canfieldite from 1 to 8mm in a minor anount of tan colored carbonate matrix. Specimens of canfieldite are very rarely seen on the market. Mining at Colquechaca originated in Spanish colonial times (mid-1500's) for its wealth of silver supplied to the Spanish crown. (MINDAT: Named in 1893 by Samuel Lewis Penfield in honor of Frederick Alexander Canfield (1849-1926), of Dover, New Jersey, USA. Canfield was a mining engineer and mineral collector. Much of Canfield's professional mining work was in New Jersey and Bolivia. Canfield was also a third generation mineral collector (having acquired his great uncles' mineral collection as well as his own father's collection). This specimen comes in an old style glass topped specimen box, like what was used at the Smithsonian long ago. I have had only two or thee for sale in twenty years.