Igneous Rocks

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Aim What are Igneous Rocks? Do Now Take out
your ESRT and turn to page 6. Look at the chart
called Scheme for Igneous Rock identification.
Using this chart answer the following
question. 1) What area of environment does
Granite form? 2) Which end of the density scale
can Gabbro be found? 3) What two textures can
Scoria have? 4) Name the minerals that make up
Diorite.
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• I. Environment of Formation
• A. Intrusive (plutonic) when magma
  cools/hardens beneath Earths surface. (intrusive
  inside)

• Magma cools slowly underground resulting in
  coarse textures.

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B. Extrusive (volcanic) - when lava cools/hardens
above the Earths surface.

• Lava cools quickly on the surface resulting in
  fine, glassy and vesicular textures.

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II. Texture
- Coarse (large) crystals - Fine (small)
crystals - Glassy (no crystals) - Vesicular
(gas pockets)
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III. Other Characteristics

• Color is described as light or dark
• Density is described as high or low
• Composition is described as
• - Mafic containing Iron (Fe) and Magnesium (Mg)
• - Felsic containing Silicon (Si) and Aluminum
  (Al)

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