The official classification of igneous rocks fills an entire book. But the great majority of real-world rocks can be classified using these graphical aids. The triangular (or ternary) QAP diagrams display mixtures of three components whereas the TAS graph is a conventional two-dimensional graph. They're also very handy for just keeping all the rock names straight. These graphs use the official classification criteria from the International Union of Geological Societies or IUGS. Click on any of them to see a larger version.
Read more:
Rock Identification Tables
Basics of Igneous Rocks
More About Igneous Rocks
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- QAP Diagram for Plutonic RocksFor granitoids and other deep-seated rocks
- QAP Diagram for Volcanic RocksFor volcanic rocks with visible grains
- TAS Diagram for Volcanic RocksThe default method for most lavas
- Graphic Index
- Text Index