Chapter 2, Section 1Chapter 2, Section 1Rocks: Mineral MixturesRocks: Mineral Mixtures

Facts

A Rock is a solid mixture of crystals of

one or more minerals.

Rocks can be classified by observing their characteristics

and properties

What are some characteristics of rocks?

The Uses and History of Rocks

Early humans used rocks as tools. Some rocks were used as

hammers, while others were used to sharpen rocks into sharp tips that could be used for arrows,

knives, and scalpels

Rocks have been used in architecture in the past as well

as in the present.

Examples: granite, marble, sandstone, and slate

Rocks can help scientists answer

questions about our Earth and

solar system

Fossils found in rocks allow scientists to learn more

about evolution and about the history of the

Earth

What are some other

uses of rock?

The Rock Cycle

The rocks in the Earth are constantly changing their

shape and composition. This process is known as the rock

cycle.

The way a rock changes determines its type. There are

3 main types of rocks: igneous, sedimentary, and

metamorphic

The Rock CycleThe Rock Cycle

SEDIMENTARY ROCK: grains of sand and sediment erode from the mountain and wash down

into a water body. Overtime as the layers build up, they are

pressed into a cement-like form.

Formation of Sedimentary RockFormation of Sedimentary Rock

The Rock CycleThe Rock Cycle

METAMORPHIC ROCK: when pieces of the Earth collide, sometimes large pieces of rock are forced downward. The sedimentary rock changes state due to the intense heat and pressure

Formation of Metamorphic RockFormation of Metamorphic Rock

Metamorphic RockMetamorphic Rock

The Rock CycleThe Rock Cycle

MAGMA: when metamorphic rock completely or partially

melts.

MagmaMagma

The Rock CycleThe Rock Cycle

IGNEOUS ROCK: Rock that forms as the magma rises to the Earth’s crust and cools

Formation of Igneous RockFormation of Igneous Rock

Igneous RockIgneous Rock

The Rock CycleThe Rock Cycle

SEDIMENT: When igneous rocks on the Earth’s crust begins to erode, it breaks

down into grains of sand and clay

SedimentSediment

Classifying Further

The 3 types of rock can be classified further based upon

their characteristics

Rocks can be classified based upon their composition. The

composition of a rock is determined by the minerals

that make up that rock

Rocks can also be classified by their texture. The texture of a

rock is created based upon the sizes of the grains it contains

• fine-grained: contains small particles

• medium-grained: contains average sized particles

• coarse-grained: contains large particles that are easily visible

Fine-Grained textureFine-Grained texture

Medium-Grained textureMedium-Grained texture

Coarse-Grained textureCoarse-Grained texture

Composition/Texture of Igneous Composition/Texture of Igneous RockRock

• The amount of time it takes for magma or lava to cool determines the texture of igneous rock

• FELSIC- lighter colored and less dense. Rich in silicon, sodium, aluminum, potassium

• MAFIC- dark colored and more dense. Rich in iron, magnesium and calcium

IGNEOUS ROCK IGNEOUS ROCK FORMATIONSFORMATIONS

INTRUSIVE – when magma cools beneath Earth’s surface

• Ex. Plutons- large balloon shaped structures formed in deep areas

EXTRUSIVE-igneous rock formed at the Earth’s surface

Ex. Volcanic rock

SEDIMENTARY ROCKSEDIMENTARY ROCK

• Formed at or near Earth’s surface without the heat and pressure.. Layers are deposited and compacted together. Layers of sedimentary rock are known as STRATA. The way in which layers are formed is called STRATIFICATION, or layering

Sedimentary rock is classified by the way it

is formed

Classification of Sed RocksClassification of Sed Rocks

• 1. CLASTIC- made from fragments of rocks and other minerals

• 2. CHEMICAL- forms from solutions of minerals and water

• 3. ORGANIC- forms from the remains of once living things

METAMORPHIC ROCKMETAMORPHIC ROCK

• How does the rock change?

• CONTACT METAMORPHISM- occurs when rock comes in contact with magna and changes the surrounding rock

• REGIONAL METAMORPHISM- occurs when a lot of pressure builds up or when large pieces of the earth collide

TEXTURE OF MET ROCKTEXTURE OF MET ROCK

• FOLLIATED- has mineral grains that are aligned by pressure.

• Ex. Shale changed into slate , then phyllite, etc

NONFOLLIATED- does not have a regular pattern of how the minerals are arranged

• Ex. Sandstone changed to quartzite