Lesson Outline LESSON 2 - readington.k12.nj.us

Name

Date

Class

Lesson Outline

LESSON 2

Igneous Rocks

A. Igneous Rock Formation

1. Igneous rock forms from molten rock in the form of

or

.

a. Lava cools

above Earth's surface.

b. Magma cools more

below Earth's surface.

2. When volcanic material erupts and cools and crystallizes on Earth's surface, it forms

a type of igneous rock called

.

a. Some extrusive rock cools so quickly that

have time to grow.

do not

b.

grow crystals.

is rock that forms when lava cools too quickly to

c. Sometimes

in the extrusive rock.

trapped in the lava escape, leaving holes

3. Igneous rocks that form as magma cools underground are called

. They contain large

because

the magma cools slowly.

B. Igneous Rock Identification

1. As with all types of rocks, the two characteristics that can help to identify igneous

rocks are

and

.

2. If the crystals are small or impossible to see without a magnifying lens, the rock

is

. If all the crystals are large enough to see and have

an interlocking texture, the rock is

.

3. Igneous rocks are classified, in part, due to their

content.

-colored minerals contain more silica.

4. Magma composition, the location where the lava or magma cools and

crystallizes, and the

determine the type of igneous rock

that forms.

Rocks

27

Name

Date

Class

Content Practice A

LESSON 2

Igneous Rocks

Directions: Complete this chart by choosing terms from the word bank and writing them in the correct spaces. Each term is used only once.

basalt lower

diorite

gabbro

molten magma pumice

granite rhyolite

higher small

large volcanic glass

Texture

5. contain

minerals

Texture

11. contain

, interlocking crystals

Examples of Intrusive Igneous Rocks

2.

3.

Igneous Rocks

1. made from

4.

Examples of Extrusive Igneous Rocks

7.

8.

9.

10.

Chemical Composition

6. have amounts of silica

Rocks

Chemical Composition

12. have amounts of silica

29

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