1. What makes Igneous Rocks special?
Today’s Objective:
What makes Igneous Rocks special?
Do Now: THINK
What are sedimentary and how are they classified?

2. Environments of Formation
ESRT pg 6

3. Environments of Formation
– rocks that
form when magma hardens beneath
Earth’s surface.
Intrusive Igneous Rock
Granite
** The slower MAGMA
cools the larger the crystals ***

4. Extrusive Igneous Rock
– When lava hardens on the Earth’s surface.
Lava cools quickly, resulting in
- Smaller crystals.
- Vesicular texture (holes).
- No Crystals at all (glassy).

5. Textures of Igneous Rocks

6. Textures of Igneous Rocks
– Slow cooling results in the formation of large crystals.
Coarse Grained
Intrusive
Fine Grained
– Rapid cooling of magma or lava results in rocks with small, interconnected mineral grains.
Extrusive

7. Glassy Texture Vesicular Texture
Ex: Obsidian
– Glassy texture results from cooling that is so fast that minerals do not have a chance to crystallize.
Extrusive
Vesicular Texture
- Vesicles (holes, pores, or cavities) are the result of gas bubbles, which often occurs during volcanic eruptions.
Ex: Pumice

8. Characteristics of Igneous Rocks

9. Composition of Igneous Rocks
– a lighter color
a lower density
- rich in Silicon (Si) and Aluminum (Al)
– a darker color
a higher density
- rich in Iron (Fe) and Magnesium (Mg)
Mafic
Felsic

10. Mineral Composition of Igneous Rocks
Rhyolite is made up of:
- Potassium feldspar
- Quartz
- Plagioclase feldspar
- Biotite (mica)
- Amphibole

11. Mineral Composition of Igneous Rocks
What is Gabbro made of?
- Plagioclase feldspar
- Biotite (mica)
Pyroxene
Olivine
Amphibole

12. Using your knowledge of earth science, your earth science reference tables and your class notes contrast Basalt and Granite in terms of how each forms, the texture of each, the color and the composition in your notebook.
Basalt
Granite
Formation
Texture
Color
Composition