Colour is best described by using primary or simple colours, with descriptors and subsidiary colours added as necessary, e.g. dull reddish-brown, pale greenish-blue. Colour variants, e.g. khaki, mauve, turquoise etc, should be avoided as these are subjective and definitions may vary from person to person.

Note: Although distinctive for some minerals, colour is often not a reliable mineral property as it can show considerable variation within a mineral. Minute amounts of impurities can change the colour of a mineral dramatically, especially that of usually colourless or white minerals. For example, quartz, which is normally colourless can be violet (amethyst), pink (rose quartz), yellow (false topaz), smoky brown-black (cairngorm), etc.

Colour variations in quartz (rose quartz and amethyst)