1. December 2, 2015 7th grade Chapter 9.2
Classifying Rocks
December 2, 2015
7th grade Chapter 9.2

2. Meme Moment
Move up if you can’t see for note-taking.

3. 3 Ways to Form Minerals
Crystallization: the process of arranging atoms/molecules so that the substance has a definite crystal structure
From solutions
From cooling lava
From organic processes
To be considered a mineral, the same thing has to also form at other times by inorganic processes
E.g. Calcite can be made by clams and coral for their exoskeleton or in caves as stalactites (and other ways)
These are the most common ways to form minerals, but there are others

4. Rocks vs Minerals
Rocks are usually mixtures of minerals and other components
Can be 1 mineral or several
4 main traits to classify rocks:
Mineral composition
Color
Texture
Origin

5. Texture Texture: the look and feel of a rock’s surface.
Texture comes from grains
Described by size, shape, and pattern of grains
Grain: particle of mineral or other rock inside a rock.
Size can be small (fine) or coarse (large)
Shape can be rounded or jagged
Pattern can be nonbanded or banded (flat lines, swirls, etc)

6. Rock Origins 3 major groups for rocks
Determine rock group based on other properties
Igneous rock: formed from cooling magma or lava
Sedimentary rock: forms when particles of other rocks, plants, or animal remains are pressed and cemented together
Metamorphic rock: when a rock is changed by heat, pressure, or chemical change, usually deep underground