The three groups of rocks are classified by:
- Grain size
- How they formed
- Chemical composition
Color is not typically used as a primary criterion for classifying rocks, although it can sometimes provide useful information about certain types of rocks. However, grain size, which refers to the size of the mineral particles that make up a rock, is an important factor in rock classification. Rocks can be classified as igneous, sedimentary, or metamorphic based on how they formed. Lastly, the chemical composition of rocks, including the minerals and elements present, is another crucial aspect of their classification.
