1. Intrusive and Extrusive Igneous Rocks
Eric Angat
Environmental Science

2. 1. What are the building blocks of rocks? 2. How are rocks classified?

3. 3. What are the parts of a volcano?
pyroclastic cloud
and ash
Crater
Lava
vent
sill
A volcano has three main parts: * A main vent. This is the main vertical channel the magma rises through to the surface. * A crater. This is the hole the lava comes out of at the top of the volcano. * A volcanic cone. These are the mountains that are made up of the rock and hard lava that accumulate near the crater when the magma comes up to the surface.
Magma conduit
Magma chamber

4. 4. What are the two types of igneous rocks?
1. Extrusive rock
formed on the surface.
2. Intrusive rock
formed underground or plutons.

5. or intrusive igneous rocks?
5. What are plutons
or intrusive igneous rocks?
A pluton  is magma that moves upward and cuts across pre-existing layers of rock.  
Plutons include
batholiths,
dikes, 
sills, 
and Laccoliths.

6. 6. Describe the different shapes of plutons or intrusive igneous rocks.
Lacolliths
dome shaped
Sill
flat shape
Dike
tabular shape
Batholiths-
large irregular shaped

7. 7. Describe basalt rock. is an extrusive rock.
Basalt rock- Igneous
Is formed from rapidly cooled lava.
Basalt is dark-gray to almost black. It is very hard and fine grained. The common minerals in basalt are plagioclase (feldspar), pyroxene, and olivine. Some of these minerals may occur as phenocrysts (large grains).
Much of basalt in Texas is exposed in eroded volcanoes. A string of basaltic volcanoes were active in the Late Cretaceous in Central and South Texas, around 80 to 100 million years ago, and much younger basalts occur at several locations in the Trans-Pecos. Basalt is used as roadbed material for railroad tracks in many places in Texas and is commonly called trap rock.
The basalt sample in the Texas Rock Kit was collected in Uvalde County and is Cretaceous in age. In Texas, no volcanoes are considered to be currently active.
It is fine grained which means it has very small crystals.

8. 8. Describe obsidian rock.
is an extrusive rock.
Obsidian rock- Igneous
Lava comes in contact with water resulting to rapid cooling.
glassy texture in the resulting rock.
Iron and magnesium give the obsidian a dark green to black color.

9. 9. Describe vesicular igneous rock.
Pumice Vesicular rock- Igneous
Pumice is a highly vesicular pyroclastic igneous rock 
Pumice - formed from quickly cooled lava. Usually lava ejected into the air by volcanic eruption.

10. 10. Describe granite rock. is an intrusive rock.
Granite rock- Igneous
Intrusions (plutons) are bodies of igneous rock that result from crystallization of magma deep underground. 
Slow cooling at depth in the Earth produces larger crystals.

11. 11. Why do intrusive rocks have bigger crystals than extrusive rocks?
Granite rock- intrusive igneous
Basalt rock- extrusive Igneous
Crystals are more evident in intrusive rocks!
Crystals are bigger in intrusive rocks because magma cools slowly. This gives time for the crystals to grow larger.

12. 12. Which of the following could
increase the rate of chemical
weathering of a rock?
moving it to a location with few
plants and animals
b. moving it to a drier climate
increasing its total surface
area
d. moving it to a colder climate