Petrology << pih TROL uh jee >> is a branch of geology that deals with the origin and composition of rocks. Petrologists analyze the physical and chemical conditions involved in the formation of the three major types of rocks: igneous, metamorphic, and sedimentary (see Rock). Such analysis helps provide clues to the origin and development of the earth.
Petrologists work both in the field and in the laboratory. They study the location, position, and distribution of rocks in nature. They use microscopic and chemical techniques to determine the minerals that make up individual rocks. In addition, petrologists attempt to reproduce in a laboratory the temperature and pressure that affect rock formations. These experiments provide data about the physical and chemical properties of rocks under varying conditions.
See also Earth (Earth’s rocks); Geology (table: The branches of geology).
