Rocks

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Rocks

• Chapter 4

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Classifying Rocks

• Mineral Composition - Look with a magnifying
  glass to determine the mineral that makes up the
  rock
• Color - Light or dark color, glassy?
• Texture look and feel of the rocks surface
• Grain size Fine, coarse or no visible grain
• Grain Shape Rounded or jagged
• Grain Pattern non-banded, banded

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Rocks

• Rock mixture of minerals, mineraloids, glass or
  organic matter
• Types of Rocks
• 1. Igneus Rock molten material inside earth or
  from a volcano cools slowly due to the insulation
  of rock allowing the atoms to arrange themselves
  into large crystals called mineral grains
• Remember magma forms from great temperatures
  (1400oC) and pressure in the earth this melts the
  minerals and forms magma
• When magma flows to the surface it is called lava

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• Intrusive Rocks formed when magma insulated and
  trapped below the earth surface, holds heat and
  cools slowly large mineral grains
• Granitic light colored rocks, lower density
  contains a lot of silicon and oxygen, mountains
• Extrusive Rocks Formed when magma cools on the
  earths surface and cools rapidly fine grained
  texture
• Basaltic dense, heavy, dark colored (magma)
  examples iron, magnesium, covers ocean floor
• Combination
• Andresitic in between basaltic and granitic in
  mineral composition

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Igneous Rocks - Texture

• IntrusiveLarge crystals
• ExtrusiveSmall Crystals (maybe not visible
  obsidian Pumice)
• MaficDark
• FelsicLight

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Obsidian
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Pumice
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Andesite
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Pumice
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Rhyolite
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Diorite-Dark color w/ large black crystals
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Basalt
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Gabbro
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Granite
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Sedimentary Rock

• Sedimentary rock -comprises 75 rocks on earth
  -formed when sediments pressed or cemented
  together may form layers
• Sediments loose materials such as rock
  fragments, grains and bits of plant and animals
• Compactation pressure causes sediments to form
  rock
• Cementation water dissolves minerals (quartz,
  calcite, hematite, limonite) natural cements
• Classification of sedimentary rock
• Clastic broken, named for size shape of
  sediments example conglomerate, breccia,
  sandstone, shale
• Chemical minerals precipitated from a solution
  or evaporates example limestone, rock salt
• Organic from once living things examples
  coal, chalk

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Sedimentary Rocks

• Compacted or Cemented (layering is key)
• Sandstone
• Shale
• Coal (rock or not? Some debate)
• Clastic
• Brecciasharp angles
• Conglomeraterounded edges (concrete)
• CoquinaShells

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Coal
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Sandstone
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Mudstone-gray silky soft
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Shale
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Conglomerate
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Breccia
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Coquina
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Coral Reefs

• Skeletons of tiny coral animals that grow
  together to form the coral reef structure
• Almost all coral reef growth occurs within 40
  meters where the light penetrates

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Metamorphic Rock

• Metamorphic rock rocks changed due to
  temperature and pressure increases or change in
  composition
• Classification of Metamorphic Rock
• Foliated mineral grains flatten and line up in
  parallel bands Example slate and gneiss
• Slate forms from shale which is arranged in
  layers when exposed to heat and pressure
• Nonfoliated no banding occurs, the mineral
  grains change, grow and rearrange but no bands
  Example is marble which forms from sedimentary
  rock calcite shiny. Hornblende and serpentine
  green. Hermatite - red

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Metamorphic Rocks

• GneissZebra strips
• SchistMetallic shine
• MarbleContains Calcite (bubbles w/HCl)
• Or Morphed sedimentary rock
• Slate (shale that has hardened)

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Gneiss
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Slate
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Schist
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Marble
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Phyllite
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Rock Cycle
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