Quartz
Description
Quartz – silicon dioxide – is the commonest and most widely occurring mineral, constituting some 12% of the earth’s crust. Its purest crystalline form is transparent, and known as rock crystal, but the solutions from which quartz crystallises frequently contain traces of other minerals, as well as bubbles of gas and water, that cannot be fitted into the crystal matrix. This image is from a ‘palmstone’ of a kind frequently found in shops selling crystal jewellery: I have scanned many of these, but find this image the most satisfying, with its subtle suggestion of flowing water or snow.