What is norite in geology ?

An ocher is a clayey earth colored red (red ocher) by fine particles of hematite (Fe₂O₃), yellow or brown-yellow by goethite (FeOOH) or "limonite". Ochres have been used as dyes since the time of cavemen. In France, Roussillon ochres (photo below) are particularly famous and have been the subject of significant exploitation.