In geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, petrifaction, petrification or silicification is the process

Taphonomy

Taphonomy is the study of decaying organisms over time and how they become fossilized . The term taphonomy was introduced to paleontology in 1940 by Russian scientist Ivan Efremov to describe the study of the transition of remains, parts, or products of organisms, from the biosphere, to the...

 by which organic material is converted into stone

Rock (geology)

In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...

 by impregnation with silica. It is a rare form of fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

ization. Petrified wood

Petrified wood

Petrified wood is the name given to a special type of fossilized remains of terrestrial vegetation. It is the result of a tree having turned completely into stone by the process of permineralization...

 is the most well known result of this process, but all organisms from bacteria to vertebrates can be petrified.


A major ingredient in the cell walls of wood is cellulose

Cellulose

Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....

. Under certain conditions the silica binds to the cellulose; when it crystallizes, it preserves the microscopic structure of wood even after the cellulose is gone.(A process of fossilization in which dissolved minerals replace organic matter)

Petrification is not the same as permineralization

Permineralization

Permineralization is a process of fossilization in which mineral deposits form internal casts of organisms. Carried by water, these minerals fill the spaces within organic tissue...

.