The recognition of colors in minerals goes back to our pre-historic ancestors
who used charcoal and iron oxides to color cave paintings which still retain
their original intensity.
Idiochromatic minerals are "self colored" due to their composition.
The color is a constant and predictable component of the mineral. Examples are
blue Azurite, red Cinnabar, and green Malachite.
Allochromatic minerals are "other colored" due to trace impurities in
their composition or defects in their structure. In this case, the color is a
variable and unpredictable property of the mineral. Examples are the blue in
Amazonite (orthoclase), yellow in Heliodor (spodumene) and the rose in rose
quartz.
Pseudochromatic minerals are "false colored" due to tricks in light
diffraction. In these cases, color is variable but a unique property of the
mineral. Examples are the colors produced by precious opal and the shiller
reflections of labradorite.
Example:"color-red*" finds all minerals with the primary color
of red or reddish. Example:color red green blue finds all minerals with those
colors. Example:color "reddish brown" finds all minerals that are
reddish brown.