Petrology is a section of geology which involves the study of rockss and the conditions by which they form. There are three branches of petrology, corresponding to the three types of rocks: igneous, metamorphic, and sedimentary.

  • Igneous petrology focuses on the genesis of rocks that crystallized from a magma.
  • Metamorphic petrology focusses the changes that a rock undergoes as a result primarly of changing conditions of pressure and temperature.
  • Sedimentary petrology focusses on the processes by which sedimentary rocks are produced.

In modern usage, the terms petrology and geochemistry are often used interchangeably; however, petrologists (those studying petrology) tend to place a greater emphasis on petrographic (thin section) mineral and textural studies, while geochemists tend to focus on geochemical analyses of rocks and whole earth geochemical cycles.