Table%20of%20Contents

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Table of Contents

• Title Metamorphic Rocks
• Page 45
• Date 12/04/12

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Objective

• Students will be able to recognize metamorphic
  rocks.
• Students will be able to explain the processes by
  which rocks are metamorphosed.

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Word of the Day

• Metamorphosis A change in form.

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Recognizing Metamorphic Rocks

• Metamorphic Rocks Rocks that have been changed.
• Metamorphic Rocks are pre-existing rocks that are
  exposed to increases in temperature and pressure,
  or hydrothermal solutions, that change the rocks
  texture, mineral composition, or chemical
  composition.

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Recognizing Metamorphic Rocks

• Increases in temperature and pressure do not melt
  the rock, but they do change it.
• High temperatures come from Earths interior.
• Rocks are either buried or located near igneous
  intrusions (magma pockets.)
• High pressures come from deep burial or from
  compression during mountain building.

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Recognizing Metamorphic Rocks

• Metamorphic Minerals - Metamorphism changes
  minerals that are present in rock to new minerals
  - solid state alterations.
• Specific minerals are associated with specific
  conditions during metamorphosis.

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Recognizing Metamorphic Rocks

• Metamorphic Textures
• 2 Kinds
• Foliated Layers and bands or minerals (stripes.)
• Bands always form perpendicular to pressure.
• Example Gneiss - formed from granitic
  rock.
• Nonfoliated Minerals that form blocky crystal
  shapes.
• Examples Quartzite - formed from quartz rich
  sandstone.
• Marble - formed from limestone.

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Recognizing Metamorphic Rocks
Quartzite - Nonfoliated
Gneiss - Foliated
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Recognizing Metamorphic Rocks

• Porphyroblasts Large crystals that have grown
  in solid rock. Surrounded by smaller crystals.
• Example Garnet