Quiz: Remember the definition of mal de mer?
A brassy yellow, metallic, tetragonal mineral, usually occurring as shapeless masses of grains. Chalcopyrite is found in igneous rocks and copper-rich shales, and it is an important ore of copper. Because of its shiny look and often yellow color, it is sometimes mistaken for gold, and for this reason it is also called fool's gold. Chemical formula: CuFeS2.