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 hosts several superb, sharp, highly lustrous, very bright, black cyclic twinned crystals measuring up to 2.5 cm across with gemmy crystals of Quartz and small tan "discs" of Siderite. A very attractive association specimen from this historic locality.