Mineral replacement is a geological process where a mineral is gradually dissolved and replaced by another mineral. This process usually takes place in hydrothermal systems or sedimentary environments, where mineral-rich fluids circulate. One common example of mineral replacement is the silicification of wood, where the organic material in wood is gradually replaced by silica. The resulting silicified wood, also known as petrified wood, retains its original structure and texture, but it is composed of quartz or other silica minerals instead of organic matter. Another notable example of mineral replacement is the formation of pseudomorphs, where a mineral occupies the space originally occupied by another mineral, retaining the shape and form of the original mineral.