Liberty Calcite

Such subtle lines as if sketched in pencil, but it is the subtle colouring that sets this apart, and made it an appropriately summery scarf in Liberty in 2012.

Calcite can be transparent or opaque and occasionally shows phosphorescence, and a transparent variety is used for optical purposes. Experiments have even been conducted using calcite as a cloak of invisibility - you can guess with what success.

More relevantly, here we have an intriguing "natural artwork" with subtleties of colour that would make many artists proud.