Mineral Species: Quartz var. Silicified Wood

Chemical Formula: SiO2

Chemical Name: Silicon Dioxide

Mineral Class: Tectosilicates

Mineral Notes: Silicified Wood, commonly also called Fossilised or Opalised Wood, is material in which the wood lignin of a tree has been gradually dissolved by water and replaced by Silica. Over time the water is gradually lost by evapouration and the Silica fuses into tiny speheres which arrange themselves into a fairly regular order. Sometimes, light entering the material is scattered producing the characteristic opalescent effect.

Description: A fragment of Silicified Wood retaining much of the original structure of the living organism. Thus the features of bark and the internal vascular system are easily seen. Otherwise, there are several areas, especially in the black-coloured zones where a colourful opalescence can be seen. 

Location: Holwood, Arizona, USA.