New Ask-a-Geologist Question: Metamorphic Foliation

Question: What term is used for metamorphic rock with banded texture?

Answer: You may be referring to “foliation” which is the layering within a metamorphic rock. Foliation occurs when there is a strong pressure applied to the rock in one direction, just like when you put your hands flat together and push. When this pressure is applied, certain minerals, like mica and chlorite, grow with their long direction perpendicular to the pressure. This make the rock appear with layering and/or banding.  This garnet schist shows a foliation of the mica mineral.

2 Responses to “New Ask-a-Geologist Question: Metamorphic Foliation”

  1. How do you make a metamorphic rock at home?

  2. There are several ways to teach children about metamorphic rocks at home. Our Rock Detectives Metamorphic Mystery kits has several experiments that you can use to illustrate metamorphic processes with household items. One of the easiest ways to describe metamorphism is that baking process. When you bake a cake or biscuits, the ingredients are the same but the heat changes them into something different. I hope this helps.

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