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 a thick chert matrix that hosts dozens of iridescent chalcopyrite crystals. 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 2 3/4 x 2 3/4 x 1 1/2 inches or 70 x 70 x 38 mm.