Mineral Species: Quartz var. Opalised Wood

Chemical Formula: SiO2

Chemical Name: Silicon Dioxide

Mineral Class: Tectosilicate

Mineral Notes: 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 evaporation and the Silica fuses into tiny spheres which arrange themselves into a fairly regular order. Light enetering the material is scattered producing the characteristic opalescent effect.

Description: A specimen of opalised wood retaining its wood-like appearance. Close inspection shows the remarkable preservation of detail including bark and inner wood. The outside is mostly opaque and grainy whilst the inside is highly opalescent and very smooth. The opal has a deep blue colour and shows the oplaescent effect well. A great display specimen of an unusual transformation of wood to semi-precious stone.

Location: Yowah, Queensland, Australia.