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Q
QuestionGeology

"How can you tell a phyllite from a schist? A. A phyllite will display light and dark bands. B. A schist will break into flat sheets. C. A schist will appear glittery due to the coarse-grained mica in it. D. None of the choices are correct."
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Answer

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Step 1:
Let's solve this geology identification problem step by step:

Step 2:
: Understand the Key Characteristics of Phyllite and Schist

- Phyllite is a low-grade metamorphic rock with a foliated (layered) texture - Schist is a medium to high-grade metamorphic rock with a more pronounced foliation

Step 3:
: Analyze Each Option

Option A: "A phyllite will display light and dark bands" - This is actually more characteristic of gneiss, not specifically phyllite - Phyllites do have a foliated appearance, but not necessarily distinct light and dark bands Option B: "A schist will break into flat sheets" - This is CORRECT - Schists have a strong foliation (schistosity) that allows them to split easily along parallel planes - This is due to the alignment of platy minerals like mica during metamorphism Option C: "A schist will appear glittery due to the coarse-grained mica in it" - This is also true and characteristic of schists - The coarse mica crystals give schists a distinctive sparkling or glittery appearance

Step 4:
: Evaluate the Options

- Option B is the most precise and definitive characteristic for distinguishing a schist - Option C is also correct, but less specific to identification

Final Answer

A schist will break into flat sheets. The key distinguishing feature of a schist is its ability to split into flat sheets due to its strongly aligned platy minerals, a property geologists call schistosity.