in physiology, denotes the conversion of wood, bones, and other substances into stone.

The fossil bodies found petrified are principally either of vegetable or animal origin, and are more or less altered from their original state, according to the different substances they have lain buried among in the earth; some of them having suffered very little change, and others being so highly impregnated with crystalline, sparry, pyritical, or other extraneous matter, as to appear mere masses of stone or lumps of the matter of the common pyrites; but they are generally of the external dimensions, and retain more or less of the internal figure of the bodies into the pores of which this matter has made its way.

The animal substances thus found petrified are sea-shells; the teeth, bony palates, and bones of fish; the bones of land animals, &c. These are found variously altered, by the infusion of stony and mineral matter into their pores; and the substance of some of them is now wholly gone, there being only stony, sparry, or other mineral matter remaining in the shape and form.