Chapter 2 Lesson 2: Classifying Rocks
• 1. What characteristic do geologists observe
when studying a rock sample?
Geologists observe the rock’s mineral
composition, color, and texture.
2. Name the three major rock groups and describe
how each forms.
Igneous- Forms from the cooling of magma or lava.
Sedimentary- Forms when small particles of rocks
or remains of plants and animals are pressed
and cemented together.
Metamorphic- Forms when a rock is changed by
heat or pressure, or by chemical reactions.
3. A material found in magma that is formed from
the elements oxygen and silicon.
_____________________________________
silica
4. Generally a light colored rock that has high silica
content._____________________
Granite
5. Generally a dark colored rock with relatively low
silica content.__________________
basalt
6. The 20 minerals that make up most of the rocks
of Earth’s crust are known as
___________________________________
Rock -forming
minerals
7. What is texture?
The look and feel of a rocks surface.
8. To describe the texture of a rock, geologists
size
use terms that are based on______________,
shape
_______________,
and,
Pattern of the grains
____________________________________.
9. Rocks with grains that are
large and easy to see
9. Fine grain or coarse grain
10. Grains that are so small they 10. Fine grain or coarse grain
can only be seen by a
microscope
11. Grains can lie in a pattern of 11.
Nonbanded or banded
flat layers or can form swirls of
colored bands
12. Have grains that do not lie in 12. Nonbanded or banded
any visible pattern
13. Rounded grain and jagged grain describe
______________
grain shape
the way that a rock formed.
14. A rock’s origin is __________________________