replacement texture

In geology, replacement texture occurs when one mineral or mineral aggregate takes on the external crystal form of a pre-existing, different mineral, a phenomenon known as pseudomorphism. This texture also describes situations where the juxtaposition of two minerals indicates that one formed at the expense of the other.1

This process is central to metasomatic replacement, where a mineralizing solution dissolves an existing mineral and simultaneously deposits a new one in its place, volume for volume. This is a key mechanism in forming epigenetic mineral deposits, including hydrothermal ore deposits and supergene sulfide enrichment. Wood petrification, where silica replaces wood fibers, is a common example of metasomatic replacement. Replacement is most effective at higher temperatures, where chemical activity is enhanced.2