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 piece features sharp, highly lustrous, somewhat gemmy, brown and black color, cyclic twinned Cassiterite crystals measuring up to 9 mm associated with small tan Siderite discs and gemmy Quartz crystals. This specimen was actually mined about 20 years ago when Viloco was really pumping out specimens.