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

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

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

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

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)

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