Small 1-2mm crystals of Canfieldite, rare silver tin sulfide, that contrast well against the light colored matrix. Canfieldite is in the Argyrodite group of minerals. From MINDAT: Named in 1893 by Samuel Lewis Penfield in honor of Frederick Alexander Canfield [April 7, 1849 Randolph, New Jersey, USA - July 3, 1926), of Dover, New Jersey, USA. Canfield was a mining engineer and mineral collector.