This calcite is from the Brushy Creek Mine, Greeley, Viburnum Trend District, Reynolds County, Missouri, USA. This mine operated primary for the recovery of lead and other metals, however, occasionally excellent specimens of the gangue minerals were found like this calcite on chalcopyrite. Calcite is a carbonate and contains the elements Ca and C while chalcopyrite is a sulfide containing Cu, Fe, and S. This specimen consists of translucent, grey, calcite crystals with over growths of chalcopyrite crystals. The calcites have dark grey phantoms. Two of the larger crystals are c-axis twins. This piece measures 5 x 4 x 3 1/2 inches or 127 x 101 x 89 mm. The largest crystal is 90 mm tall.