The photomicrography below was made with a thin section of Cretaceous-era petrified wood recovered from Wise County, Texas. A combination of Hoffman modulation contrast and polarized light illumination with a first-order retardation plate yields a colorful pseudo three-dimensional image of the fossilized wood.

Petrified wood arises from mineral replacement inside the trunks and limbs of trees from primeval forests that became buried in thick layers of sediments millions of years ago. The wood fiber is slowly replaced by tiny crystallites of silica (usually in the form of agate) over long periods of time. Environmental factors like temperature and pressure as well as the presence of inorganic compounds such as manganese, copper, and iron oxides affect the color and microscopic structure of petrified wood.