Metamorphic Rocks

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Metamorphic Rocks
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• Metamorphic rocks just igneous or sedimentary
  rocks that went through HEAT and PRESSURE.
• They did not melt completely, otherwise theyd
  have cooled and formed more igneous rocks.
• Instead they were heated, deformed, warped,
  twisted, bent, or squished into the rocks in your
  boxes.

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How to identify

• Foliation The 1 property. Foliated rocks show
  layering.

Gneiss has banded layers
Slate has shaley flat layers
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• It gets better!
• Foliated textures also include Phyllites wavy
  appearance

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• And Schists, well, Schistose texture.

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• So the foliated textures go like this
• Slate (flat)
• Phyllite (Wavy)
• Schist (Crumbly, yet still
  foliated)
• Gneiss (Banded)

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Grain Size

• Gneiss is much coarser than slate, so with
  foliated rocks grain-size is helpful.
• Marble can be either chunky or have no visible
  grains, so is often microcrystalline.

Marble
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What minerals can you see?

• Or is it simply light or dark?

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For Today

• Work through the 10 samples in the box.
• Then well do a Topo-map review activity.