These cuprite crystals are from the Milpillas Mine in Cuitaca, Mun de Santa Cruz, Sonora, Mexico. Mining at this locale began in 2006 with the extraction of copper minerals. Thirty-six mineral species have been identified at the mine including cuprite. It is a secondary mineral found in oxidized copper ore bodies and it contains the elements Cu, C and O. Mining started in several copper oxide zones where outstanding secondary copper mineral specimens were recovered. This specimen consists of a mostly quartz matrix, partially sawed on the back side, that contains exposed veins and vugs that are filled with dozens of lustrous cuprite crystals.The crystals range in morphology from tabular to dipyramidal. Their luster is sub-metallic. This piece measures 3 x 2 1/2 x 1 14 inches or 76 x 63 x 32 mm.