Formation of fossilized wood

One of the presuppositions with it wood can fossilize is the necessity to expel a rotting of the wood. A cover with volcanic ash or sediments and the break connected with it of the oxygen supply and protection from micro-organisms can create these presuppositions.

Furthermore a suitable solution as for example silicic acid (SiO2) is necessary to the petrifaction of a wood which can penetrate into the wood and replaces, in this connection,the organic materials of the wood.

If a such solution does not exist, cabbage or anthracite can appear from the wood according to time, pressure and temperature conditions . The such reorganization process of vegetable materials is called Inkohlung. (In this connection, e.g., peat, brown coal, coal, anthracite, graphite) can survive the structure of the wood.

The exact expiration of the petrifaction is controversial. One of the theories says that the hollow cavities within the cells and their walls are filled with inorganic material, while another theory assumes of the fact that a slow molecule exchange takes place by which organic material is replaced with the inorganic.

Fossilized wood appears where are bigger amounts of silicic acid. One finds an occurence of this kind in volcanic deposits and sediments of rivers and seas/lakes, So many fossilized forests are to be found in areas with (earlier) volcanic activity.

By the penetration of silicic acid (SiO2) in the wood it does form first amorphous SiO2 which is not stable and converts itself about opal A and OPAL CT., finally, to quartz. The speed of the crystallization is dependent among other things on the pressure and temperature conditions. During the crossing of opal to quartz the structure of the wood can get lost. With most fossilized wood the silicic acid is present as a Chalcedon.

The colouring of the fossilized wood is a consequence of the chemical composition of the solution, as a rule iron, manganese or copper. Because silicic acid is colorless / white, the colouring of the fossilized wood is determined by the kind and amount of these elements. So arise, e.g., the following colour hues: