1. Rocks: Mineral Mixtures
Chapter 4
Rocks: Mineral Mixtures

2. Section 1: Understanding Rock
The Earth’s crust is made up mostly of rock
Rock – is simply a solid mixture of crystals of one or more minerals
Rocks come in all shapes and sizes

3. The Value of Rock
Rock has been an important natural resource for as long as humans have existed
Early humans used rocks as hammers and to make other tools
Arrowheads and knifes were made out of rock
Rocks have also been used for centuries to make buildings, roads, and monuments
Concrete is one of the most common building materials today
Rock is also very important to scientists
What can be found by scientists in rock that give us clues and evidence about past life on Earth?

4. The Rock Cycle The rocks in the Earth’s crust are constantly changing
The way that rock forms determines what type of rock it is
The three major types of rocks are;
1) Igneous – is rock that forms from the cooling of magma.
Magma forms in the Earth’s lower crust and upper mantle
2) Sedimentary – is rock that forms when sediments are compacted and cemented together
The sediments that form this rock come from weathering and erosion
3) Metamorphic – is rock that forms when the texture and composition of a preexisting rock is changed by heat or pressure deep underground

5. (see page 83)

6. The Nitty-Gritty on Rock Classification
You now know that rocks are classified into three main categories
But these three main groups can be broken down into smaller groups based on how and where the rock is formed
Scientists use composition and texture to further classify rocks
Composition – is the minerals that the rock are made of
Texture – is determined by the size, shape, and grain positions of the rock
The texture of a rock is a good clue to how and where the rock formed

8. Chapter 4 – Quiz 1
1) ________ is simply a solid mixture of crystals of one or more minerals
2) ________ is rock that forms from the cooling of magma.
3) ________ is rock that forms when sediments are compacted and cemented together
4) ________ is the minerals that the rock are made of
5) ________ is determined by the size, shape, and grain positions of the rock
Bonus - _________ is when magma cools beneath the Earth’s surface

9. Answers 1) Rock 2) Igneous 3) Sedimentary 4) Composition 5) Texture
Bonus - Intrusive

10. Section 2: Igneous Rock

11. Origins of Igneous Rock
The word igneous comes from the Latin word for “fire”
When magma or lava cools down enough it forms igneous rock
There are three ways that magma can form;
1) Temperature
Deep within the Earth temperatures are high enough to melt rock
2) Pressure
Hot rocks under extreme pressure will not melt until the pressure is released
3) Composition
When the composition of the rock changes

12. Igneous Rock Formations
Intrusive – when magma cools beneath the Earth’s surface
Intrusive rock formations are name for their size and the way they push into the surrounding rock
Extrusive – igneous rock that forms on the Earth’s surface
Most volcanic rock is extrusive

13. Section 3: Sedimentary Rock
Through the process of erosion, sediment is formed and transported from one place to another
As new layers of sediment are deposited they eventually become compressed which causes the sediments to become “glued” together
Sedimentary rock forms near or at the Earth’s surface
The most noticeable feature of sedimentary rock is its layers – strata

15. Composition of Sedimentary Rock
Classic Sedimentary Rock
Sedimentary rock made of fragments of other rocks and minerals
Chemical Sedimentary Rock
Sedimentary rock formed from solutions of minerals and water
This happens as rain water slowly makes its way to the ocean
As it travels it dissolves some of the rock mineral it passes through
Types include rock salt and limestone

16. Sedimentary Rock Structures
Many sedimentary rock features can tell you about the way the rock formed
Stratification – how sedimentary rock is layered

17. Section 4: Metamorphic Rock
The word metamorphic comes from the meta, meaning “changed” and morphos, meaning “shape”
Rock can undergo “metaporphism” by heat, pressure, or a combination of both

18. Origins of Metamorphic Rock
Most metamorphic

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