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 wedge shaped limestone matrix that contains dozens of chalcopyrite crystals and crystal clusters. They have a brilliant iridescence in a wide array of colors that changes with the direction of the light source. Their morphology is tetragonal and many display crystal twinning. This piece measures 2 1/2 x 2 x 1 1/4 inches or 63 x 50 x 32 mm.