Ch 4 Igneous Rocks (Page 2 of 3) in pdf

Ch 4 Igneous Rocks Page 2

C. Classification of Igneous Rocks

1. Recognizing Igneous Rocks

___________________ (Volcanic) - magma erupts on surface - lava

b. ___________________ (Plutonic) - magma solidifies within crust

2. Kinds of Magma

a. _________ - light colored, high silica rock (thick) Feldspar and silica

Ex. Granite

b. __________ - dark colored, low silica rock (thinner) Mg and Fe

Ex. Basalt

c. ____________ - very high concentration of Mg and Fe

d. _____________ - composition between granite and basalt

2. Texture - depends on _________, shape, and arrangement of mineral grains, or crystals

How fast it cools- slow cooling produces larger crystals

Ex.

Fast cooling produces smaller crystals

Ex.

Very fast cooling produces glassy

Ex.

Amount of __________ dissolved - more gas smaller crystals

c. Porphyritic texture - two different textures

____________________ - Larger crystal embedded in fine-grained matrix

D. Naming Igneous Rocks

Kinds of Magma

Coarse Grain

Fine Grain

Glassy

Felsic (light colored)

Intermediate

Mafic (dark colored)

Ultramafic

Ch 4 Igneous Rocks Page 2