Opaque

Opaque is a term used to describe a material that disallows the passage of enough wavelengths of light to render it non-transparent, i.e. cannot be seen through. Examples of minerals that are often classified as opaque include Pyrite, Chalcopyrite, Galena, Hematite, Wulfenite, Magnetite, Stibnite, Goethite, Limonite, Covellite , and Schalenblende.