Neomineralization

Neomineralization is a geological process where new minerals form within existing rocks or sediments. This formation occurs under specific conditions of pressure, temperature, and chemical environment that differ from those under which the original minerals formed. It is a key aspect of rock alteration and weathering, playing a significant role in the long-term evolution of Earth's crust.

This process can happen through several mechanisms. One common pathway is diagenesis, which refers to the physical and chemical changes that occur in sediments after deposition but before metamorphism. During diagenesis, pore fluids can introduce new chemical elements, or existing elements can rearrange to form stable new mineral phases under the prevailing conditions. Another significant mechanism is weathering, where rocks exposed at the Earth's surface are broken down by physical, chemical, and biological processes. Chemical weathering, in particular, can lead to the dissolution of original minerals and the precipitation of new, more stable minerals like clays and oxides.

Metamorphism also involves neomineralization, as heat and pressure cause existing minerals to recrystallize or react to form new minerals stable at the higher metamorphic grades. Hydrothermal alteration, driven by hot, chemically active fluids circulating through rocks, is another important process leading to neomineralization. These fluids can dissolve original minerals and precipitate new ones, significantly changing the rock's composition and texture. Understanding neomineralization is crucial for fields such as geology, soil science, and environmental science, as it impacts mineral resource formation, soil fertility, and the fate of contaminants.