Muscovite Schist
What is a schist?
Schist is a medium-grained metamorphic rock showing very notable signs of chistosity. It is usually formed through the evolution of mudstone/shale or even some igneous rocks. The structure of this rock tends to cut into flakes and/or slabs.
What is Muscovite schist?
Muscovite schist: A rock in which the visible mineral in this schist is muscovite. Its platy grains are aligned in a common orientation, and that allows the rock to be split easily in the direction of the grain orientation.
Formation
Schistosity is a mode of foliation that happens in certain metamorphic rocks. This foliation is caused by the parallel alignment of the minerals within the rock. The schistosity develops perpendicular to the direction of greatest compression which is also called shortening direction. The development of Schistosity occurs at higher temperatures when the rock is strongly compressed. The composition of the rock must permit formation of abundant platy minerals. Early stages of metamorphism convert mudstone to a very fine-grained metamorphic rock called slate. Platy minerals found in schists include chlorite, talc, and graphite.
QUESTIONS/TASKS:
1. Examine the schist along this formation. How wide do you estimate each layer to be? What is the direction of the layers here? What does that tell you about the greatest compression here?
2. Is this formation smooth to the touch or rough and grainy? Pick up a piece from where you are standing. Is it delicate and easily broken or is it a very tough rock?
3. Tell us what you believe contributes to the coloration of the formation here?
4. To prove that you were here, please post a picture of yourself or your GPS with the the formation in the background. Any other photos of the area are also greatly appreciated.
Reference:
Wikipedia Schist Article: https://en.wikipedia.org/wiki/Schist