13.5: How Do I Identify Metamorphic Rocks?

How Do I Identify Metamorphic Rocks?

All metamorphic rocks are identified by their mineral content and texture. For metamorphic rocks, texture Links to an external site. refers primarily to the orientation of the minerals in the rock. Additionally, crystal size can also convey important information regarding the temperature and pressure conditions during metamorphism.

To identify metamorphic rocks, you will first need to determine if the rock is foliated or non-foliated. Examine the rock for evidence of any pattern or foliation, and if present, identify the size and mineral(s) that compose the foliation pattern (Figure 13.8, left). Non-foliated metamorphic rocks can be identified by the properties associated with their dominant composition (Figure 13.8, right).