1. Igneous Rocks- The Original Earth!
Earth formed from a HUGE ball of molten rock material called MAGMA
Over MILLIONS of years, it cooled and solidified into IGNEOUS rock!
Igneous Rock still forms the same way:
COOLING, CRYSTALLIZATION and SOLIDIFICATION of magma

2. Igneous Rocks- Cooling and Solidification
Magma: melted rock BELOW the surface
Lava: melted rock ABOVE the surface
INTRUSIVE igneous rock: forms from MAGMA
EXTRUSIVE igneous rock forms from LAVA
All igneous rock forms from cooling and solidification of magma!

3. Igneous Rocks- Review What are all igneous rocks made from?
Extrusive igneous rocks are made from lava or magma?
Intrusive igneous rocks are made from lava or magma?
Extrusive rocks form on/below the surface of Earth
________ rocks form below Earth’s surface

4. Igneous Rocks- Different Types
Scheme For Igneous Rock Identification p6
Texture
Extrusive
Cool FAST!
Glassy- NO crystals…
SMOOTH!
Fine- Small crystals
Intrusive
Cool SLOW
Coarse-Large crystals!
ROUGH!
Very Coarse-
Very Large Crystals
Vesicular: Extrusive rocks that have gas pockets

5. Igneous Rocks- Review
Extrusive igneous rocks are smooth/rough textured because they are made from small/large crystals?
Intrusive igneous rocks are smooth/rough textured because they are made from small/large crystals?

6. Igneous Rocks- Different Types
Scheme For Igneous Rock Identification
Extrusive Igneous Rocks
Obsidian Basalt Glass
Pumice* Scoria*
Rhyolite Basalt
And others…
Intrusive Igneous Rocks
Granite Diorite
Gabbro Pegmatite
*Vesicular Rocks:
Extrusive rocks that contain gas pockets

7. Igneous Rocks- Different Types
Scheme For Igneous Rock Identification
Characteristics
FELSIC: Made with light color, low density minerals
MAFIC: Made with dark color high density minerals
Andesite and Diorite are intermediate rocks!
Mixed felsic and mafic!

8. Igneous Rocks- Review Name 2 FELSIC igneous rocks.
FELSIC rocks are dark/light color with low/high density.
Name 2 MAFIC igneous rocks.
MAFIC rocks are dark/light color with low/high density.
Name two rocks that combine both felsic and mafic characteristics.

9. Igneous Rocks- Different Types
Scheme For Igneous Rock Identification
Mineral Composition
FELSIC: Mostly potassium feldspar, quartz and plagioclase feldspar
MAFIC: Mostly plagioclase feldspar, pyroxene, olivine
Andesite and Diorite are intermediate rocks!
“Mono” = one mineral
“Poly” = multiple minerals

10. Igneous Rocks- Review
FELSIC rocks contain mostly quartz and potassium feldspar/pyroxene and olivine.
MAFIC rocks contain mostly quartz and potassium feldspar/pyroxene and olivine.
What does it mean that diorite and andesite are intermediate?
Anorthosite is a monomineralic form of granite. It makes up most of the High Peaks in the Adirondacks. It is light gray/white in color. Is it mafic or felsic? What mineral does it likely contain?

11. Igneous Rocks- Final Review
What’s the difference between intrusive and extrusive igneous rocks?
What’s the difference between FELSIC and MAFIC rocks?
What are the main minerals in high density igneous rocks?
What are the main minerals in low density igneous rocks?
Name an intrusive MAFIC igneous rock.
Name an vesicular mafic rock: Is it intrusive or extrusive?

12. Summary Questions…
7. Why do intrusive rocks have large crystals while extrusive rocks have small crystals?
8. Which graph correctly shows cooling times for the three rocks?
A B C.

13. Igneous Rocks- Review
Name 2 igneous extrusive rocks that are not vesicular.
Name 2 igneous extrusive rocks that are are vesicular
Name 2 igneous intrusive rocks.
Igneous extrusive rocks are never/sometimes/usually vesicular.

14. Igneous Rocks Vocabulary
Magma Lava Igneous
Intrusive Extrusive Glassy
Texture Vesicular Mafic
Felsic Monomineralic Grain Size

15. Rock Formation: Igneous Rock
How do igneous EXTRUSIVE rocks form?
Crystallization and Solidification of lava
Lava erupts onto the surface!
..And cools quickly to form extrusive rocks
Rhyolite and basalt form this way
Igneous EXTRUSIVE rocks cool quickly and have small crystals!!
Lava erupts onto the lithosphere!