Cassiterite from Amo Sn deposit, Yunnan, China

Transparent crystals of cassiterite with an average size of over 25 mm with a glassy lustre and abundant twinning. The cassiterite is associated not only with quartz but with a cluster of metallic cosalite (an uncommon lead bismuth sulfosalt), as analysed by the University of Arizona. In this respect, this specimen appears to be unique as I have not found any record of another piece with cosalite from this locality. Cassiterite from this deposit is relatively rare compared to the abundant specimens (which are black and opaque: see examples in my collection) from Pingwu. The specimen came out in about 2010.

Photo by László Kupi