Tangerine quartz
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.
Quartz (silicon dioxide), or rock crystal, itself has piezoelectric and pyroelectric properties which means it will undergo any manner of transformations when subjected to pressure or heat, or in the presence of other electro-magnetic charges (even human). Such changes do, of course, occur naturally in the earth and it seems that tangerine quartz is created while quartz is in the presence of of haematite dust (iron oxide) in intense heat causing the iron to adhere and create this wonderful colour. It is also referred to as haematised quartz. The Mineralology of Novia Scotia website contains good explanations of this and other types of minerals. See another picture of the tangerine quartz on courgettelawn’s flickr blog (that’s mine).
What a literally brilliant orange thing!