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, sawed on the back side that contains an exposed vein that is filled with dozens of cuprite crystals. Their morphology varies from tabular to octahedral to bi-pyramidal and hoppered. Their luster metallic or mirror-like and they have a red hue. This piece measures 2 x 1 1/4 x 5/8 inches or 50 x 32 x 16 mm.