Chalcopyrite with garnet, magnetite and quartz from New Mexico
This sample of metamorphic rock from New Mexico has four distinct minerals present. Chalcopyrite, CuFeS2 (copper iron sulfide), is the gold, or yellow colored mineral. Garnet is red and glassy looking, and is mostly a variety called almandine, Fe3Al2Si3O12. Magnetite is the gray mineral, Fe3O4 (iron oxide). Finally, quartz is the white mineral present in this sample. Its formula is SiO2 (silicon dioxide). This specimen is 9 cm across.
University of North Dakota Mineralogy Collection, #113