perminéralisation

Permineralisation (British English: permineralisation) is a form of fossilization in which mineral-rich groundwater or fluids infiltrate the porous parts of organic material and precipitate minerals within its tissues. The original material is often retained, and the result is a three-dimensional, mineral-filled replica that preserves fine internal details.

As groundwater flows through pores and voids, minerals such as silica (SiO2), calcite (CaCO3), apatite, or iron sulfides (pyrite) precipitate, filling spaces and reinforcing the structure. The process can preserve microstructures like cell walls, vascular tissue in wood, or bone microarchitecture.

Permineralisation typically occurs during diagenesis, sometimes early after burial, in environments with chemical-rich fluids and relatively low oxygen. It can take thousands to millions of years.

It is distinct from replacement, which dissolves the original material and substitutes another mineral entirely; permineralisation often leaves the original organic framework intact while filling pores. Classic examples include petrified wood and fossil bones where silica, calcite, or phosphate has permeated the tissue.

Related variants include pyritization, where iron sulfide fills tissues under anoxic conditions. Permineralisation is one of several diagenetic pathways that produce fossil preservation.