“…Copper compounds provide a wide range of colors, from various shades of blue to red, depending on their chemical state (oxidation states, crystal structures, ligands, etc. ). − Numerous historic pigments are copper-based, and artists’ treatises contain guidelines for their preparation and use (supported by modern analytical investigation), e.g., blue azurite (Cu 3 (CO 3 ) 2 (OH) 2 ) for Mary in Christian depictions. − Because of the varying interpretation of these historical synthesis descriptions, these pigments provide interesting and challenging real world, artistic, and historic examples for students.…”