Milpillas Mine, Cuitaca, Mun. de Santa Cruz, Sonora, Mexico
This is a Siderite from Milpillas Mine, Cuitaca, Mun. de Santa Cruz, Sonora, Mexico. This is one of only a dozen pieces we obtained from a single small pocket of siderites found sometime in August 2013, at the sharp contact zone boundary layer between the surface oxidation zone (which has produced all the recent azurites and malachites from this mine), and the solid chalcocite ore body beneath.