Yesterday, I bought an amazing bed of tangerine quartz. Today, I have been trying to find out what causes the fabulous tangerine-orange hue. The colouring is translucent and comes from the surfaces of the quartz, rather than from the inclusion of a foreign mineral within. Tom (my extremely excellent other half) asked about what causes the similar but man-made effects displayed by aqua, ruby and opal aura quartz and Dave Watts (a mineral dealer) and Ian Williams (a physicist) explained that the effects are created by a process called Thin-film Deposition, also referred to as the ‘plasma treatment’ where (explained simply by me) clear quartz is placed in a vacuous chamber in the presence of metallic particles such as gold, silver or platinum. Then, a low-voltage current is passed through the quartz and the metal particles adhere, electrostatically, to the quartz creating hues of irridescent blue, ruby red, and irridescent pearl or white respectively.