This specimen was found about 5-6 months ago (2009), and is one of the more interesting Cassiterite association specimens that I have seen in years. Bolivia has probably produced more tin than any other country in the world. The great tin mines at Viloco (sometimes called Araca) have produced some of the most magnificent Cassiterite specimens extant. This particular specimen host of several fine, sharp, rather lustrous, black cyclic twinned crystals measuring up to 9 mm across which are associated with very eye-catching Quartz crystals that actually have small Smoky Quartz "phantoms" in the center of the prisms.