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 consists of one particular superb quality, sharp, highly lustrous, very dark brown (slightly gemmy) cyclic twinned crystal measuring a whopping 4.2 cm across and associated with smaller cyclic twins on minor Quartz. To find a twin of this size and quality from Viloco is extremely rare, and this piece dates back over 40 years ago when some of the finest Cassiterites were mined at Viloco. Ex. Richard Kosnar Collection.