Name: _____________
Igneous Rocks – Classified by Magma Type
Introduction:
* Just to review, we know that basaltic magma/lava is high in ______ & _________ which is the
reason they are so dense.
* Granitic magma/lava, on the other hand, is high in _________ & ________, making these igneous
rocks less dense than basaltic ones.
* Because of the elements that make up these magmas, basaltic rocks have a ____________
color than granitic and andesitic rocks.
* Andesitic magma/lava has an intermediate amount of silica and heavy elements, giving it a
medium color and a medium density.
* Keep these numbers in the back of your head
Granitic > 66% SiO2
Andesitic 66% - 52% SiO2
Basaltic <52% SiO2
Now, let’s apply that knowledge.

You find a very dark colored igneous rock on the ground. Being an expert geologist, make
a hypothesis about the amount of silica in that rock and tell your friend how you knew
this.

You find three beautiful rocks in room 236 and you arrange them from lightest to darkest
on the table. Tell me how dense they would each feel compared to each other.

You find a rock that you take home to your lab and analyze for silica content. You find
that it has about 54% silica. What type of igneous rock is it and what color?

You find a very light colored rock in the lunch room (you test it and make sure it isn’t a
tater tot). Can you tell by the color whether it formed inside or outside the Earth? What
could help you figure out the location of its formation?

Two granitic rocks are in Mr. Hayden’s room, but one seems much more dense than the
other. Make a hypothesis about the silica contents of each rock.
1. (True/False) There is a definite path that all rocks take through the rock cycle.
2. James ___________________ named the rock cycle in 1788.
3. What are the two types of metamorphic rocks?
4. What are the three types of magma/lava?
5. Give an example of an extrusive rock. What size crystals do you think it would have?
6. Give an example of a foliated rock.
7. Give an example of an intrusive igneous rock.
8. What type of sedimentary rock is made from pieces of broken rock?
9. What type of sedimentary rock is made from once-living things?
10. Intrusive rocks are formed _______________ the Earth and have _____________-sized crystals.
11. Rocks are made of _________________________, _______________________ & _________________________.
12. Give an example of a chemical rock and tell how it formed.
13. _____________________ metamorphic rocks show layers, or bands.
14. ___________________ are rocks made from magma or lava.
15. Metamorphic rocks are made from the processes ______________ & __________________.
16. Name two metamorphic rocks, whether they are foliated or nonfoliated, and their parent rocks.