Petrification is preservation of biological material in a stone-like form through mineral deposition and/or replacement. In permineralization, dissolved material precipitates within pores and spaces; replacement instead substitutes mineral material for some original substance. The processes can occur together, so a detailed fossil can retain structural information even when much of its chemistry has changed.
Silicified wood supplies a motivating experiment. Hisatada Akahane and colleagues studied wood in silica-rich hot-spring water, where silica spheres accumulated on split surfaces and cell walls. The observed textures resembled some naturally silicified wood in the fossil record.[ref]
The result shows that appreciable mineral deposition can proceed rapidly under suitable chemical conditions. It does not assign one universal duration to petrification, prove complete replacement of all organic matter, or determine the age of the surrounding rock.
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