Chapter 4

Question 1

What are the two types of igneous rocks?

Answer 1

Extrusives and Intrusives

Question 2

Intrusives

Answer 2

Igneous rocks that cool slowly underground. Have large crystals. Ex: Granite

Question 3

Extrusives

Answer 3

Igneous rocks that cool quickly on the surface. Have tiny crystals or are glassy. Ex: Obsidian and pumice

Question 4

Aphanitic

Answer 4

An extrusive texture where the crystals are too fine to be distinguished with out a microscope. Comes from magma cooling quickly.

Question 5

Pyroclastic

Answer 5

Material fragments ejected explosively into the air. Ex: Pumice, ash, tuff

Question 6

Glassy

Answer 6

Mo minerals present and looks like glass

Question 7

Vesicular

Answer 7

Void spaces where there were gas bubbles.

Question 8

Porphyritic

Answer 8

Mixed texture. Shows that there were two cooling processes.

Question 9

Phaneritic

Answer 9

Coarse and crystalline texture. Comes from slow cooling.

Question 10

Pegmatitic

Answer 10

Extremely coarse and crystalline.

Question 11

Mafic

Answer 11

Low percentage of silica. Is dark colored.

Question 12

Intermediate

Answer 12

Intermediate percentage of silica and is a intermediate color.

Question 13

Felsic

Answer 13

High percentage of silica. Light in color.

Question 14

Volcano

Answer 14

A hill or mountain that forms from the accumulation of lava that erupts at the surface.

Question 15

Plutons

Answer 15

Large igneous bodies that cool underground. Intrusive.

Question 16

Sill

Answer 16

Horizontal intrusions

Question 17

Dike

Answer 17

Vertical or semi-vertical intrusion