Definition

Petrology (from the Ancient Greek: πέτρος, romanized: pétros, lit. ‘rock’ and λόγος, lógos) is the branch of geology that studies rocks and the conditions under which they form.

The field of petrology is traditionally split into three subcategories: igneous, metamorphic, and sedimentary petrology. Click on the pull-down menu below to explore the definitions of these sub-fields:

At the university level, igneous and metamorphic petrology are traditionally (but not always) taught together because they both contain heavy use of chemistry, chemical methods, and phase diagrams (Teaching Mineralogy and Petrology). Sedimentary petrology is more commonly taught as a stand-alone class or together with stratigraphy because stratigraphy deals with the processes that form sedimentary rocks.  Introduction to Petrology covers igneous and metamorphic petrology for this reason.

However, it is increasingly common for mineralogy and petrology (sometimes igneous, metamorphic, and sedimentary) to be combined into a semester- or year-long Earth Materials course.  The modular structure of this online book is designed so that students and instructors can use the modules relevant to the course at their college or university.

Key Aspects of Petrology

Click on the pull-down menu below to explore some of the ways scientists study igneous and metamorphic rocks:

Attributions
Introduction to Petrology by Elizabeth Johnson, Juhong Christie Liu, and Mark Peale is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

This chapter contains material from “Petrology” by Wikipedia which is licensed under CC BY-SA 4.0.