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Date:
Geology 12: Metamorphic Rock ID and Terms Practice
Parent Rock: Shale
Metamorphic Product: Gneiss
1. Shale is composed of clay mineral grains that are not visible to the unaided eye. However, Shale’s
metamorphic product Gneiss is composed of coarse muscovite and biotite mineral grains (among other
minerals, but you don’t need to worry about these right now).
a) Name and explain the process through which very fine grained clay minerals become coarse grained
muscovite and biotite minerals.
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b) What useful information can the presence of muscovite and biotite reveal about the formation of
Gneiss?
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2. a) Define foliation
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b) Circle the rock sample below that exhibits foliation.
3. Both of the rock samples below exhibit foliation. Identify the sample that was formed at a greater
metamorphic grade (higher temperature and pressure) and explain how you know this. You do not need
to reference table 7.15 in your lab book to answer this question!
Sample A
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Sample B
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