earthstory: Green petrified woodSome 200 million years ago in the Triassic of what is now the Gokwe
earthstory: Green petrified woodSome 200 million years ago in the Triassic of what is now the Gokwe area of Zimbabwe as forest of Woodowrthia and other trees was engulfed in volcanic ash and slowly petrified into varied types of silica as this element was dissolved and remobilised by circulating waters. The piece of log in the photos is 18cm long by 6 across and coloured green by the presence of chromium, while its fossilised bark displays clearly where the tree’s spines once were. At some point in its long journey to the present through geological time, chromium rich waters passed through the buried stone forest and deposited salts, resulting in the deep green tinge that acts as a hygrometer, since it turns greener the more humidity is in the air. Chromium is a common agent of colour in gems, giving us the red of Rubies (http://on.fb.me/1gQbjaj) and the lovely greens of gems such as Emerald, Chrome Tourmaline (http://on.fb.me/1ixYQcu) and Tsavorite Garnet ( http://on.fb.me/1ygBzM5).LozImage credit: LGF Foundationhttps://lgfmuseum.org/ -- source link