Rocks With Wavy Layers Are Foliated Metamorphic Rocks!

Do you see the little wavy layers in the pictures of foliated metamorphic rocks below? All three of these rocks formed from a sedimentary rock called shale. With different amounts of metamorphism, shale becomes different types of rocks!



(click for larger image)

Features How Much Metamorphism?

(Courtesy NPS)

It looks like shale because it is dark in color and will break into thin flat layers like shale often does. Unlike shale, slate makes a ringing sound when you hit two pieces together. Low

(Courtesy NPS)

There are several different types of schist such as mica schist, garnet schist, and chlorite schist depending on which minerals are found in the rock. All schist contains mica. Medium
Gneiss (pronounced "nice")

(Courtesy USGS)

This striped rock often looks a bit like fudge swirl ice cream. The light colored layers are usually quartz and feldspar and the dark layers (the fudge!) are mostly mica. High
Last modified August 11, 2003 by Lisa Gardiner.

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