These chalcopyrite crystals are from the Sweetwater Mine in Ellington, Viburnum Trend District, Reynolds County, Missouri, USA. This is primarily a lead-zinc ore body that contains twenty-three different species of minerals including chalcopyrite. It is a copper sulfide that contains the elements Cu, Fe and S. This specimen consists of is a thick, mound shaped, layer of crystals on a thin matrix core. They have a brilliant iridescence in a wide array of colors that changes with the direction of the light source. Their morphology is tetragonal with multiple twinning that forms spherical and rosette clusters. This piece measures 3 x 2 x 1 3/8 inches or 76 x 50 x 35 mm.