The earthy form of haematite is red ochre, yellow ochre is an earthy from of limonite (a mix of iron hydroxides and oxides). Both red and yellow ochre is used as a pigment and is often used as body paint with a spiritual significance by many tribal peoples across the world.
ISO standards define various industrial and chemical properties, and how to test for them. The principal ISO standards that relate to all pigments are as follows:
ISO-787 General methods of test for pigments and extenders ISO-8780 Methods of dispersion for assessment of dispersion characteristics