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)
||How Much Metamorphism?
|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.
|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.
|Gneiss (pronounced "nice")
|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.
Last modified August 11, 2003 by Lisa Gardiner.
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The Fall 2010 issue of The Earth Scientist
, focuses on rocks and minerals, including articles on minerals and mining, the use of minerals in society, and rare earth minerals, and includes 3 posters!
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