A fine miniature of the rare copper, water and hydroxide bearing polyvanadate, Volborthite, from Milpillas mine at Cuitaca, Mun. de Santa Cruz, Sonora, Mexico. Milpillas works a series of copper veins and began operating in 2006, with a life expectancy until 2027. Mine policy is against the collection of specimens by both miners and visiting mineral dealers, making the supply of good material rather limited. This mine is famous for its excellent specimens of Volborthite and this is a very fine example with the intensely dark olive green bladed crystals perched on top of light peppermint green Malachite which coats the underlying matrix. Volborthite is a mineral species not commonly encountered, be this in the field or in a collection, hence great specimens such as this show the species at its best!