Rocks and Minerals

Rocks and Minerals

Middle School

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Learning Objectives

• Define a rock and identify the three main types: igneous, sedimentary, and metamorphic.

• Describe the rock cycle as a continuous process with key transformations.

• Explain how the three rock types form, including intrusive and extrusive rocks.

• Give examples and common uses for each of the three main rock types.

Key Vocabulary

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Rock

A naturally formed, non-living Earth material made of mineral grains held together in a solid mass.

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Mineral

A naturally-occurring, inorganic solid with a specific structure and a definite, unvarying chemical composition.

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Magma

Extremely hot, molten rock found deep beneath the Earth's surface from which some igneous rocks form.

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Lava

Molten rock that erupts onto the Earth's surface, from which some types of igneous rocks form.

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Sediments

Small, solid pieces of material from rocks or living things that form sedimentary rocks.

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Rock Cycle

A continuous process where rocks change from one type to another over very long periods.

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What are Rocks and Minerals?

Rocks

• ​Rocks are naturally formed, non-living materials found on Earth.

• ​​They are made up of different mineral grains held tightly together.

• ​We identify rocks by their mineral content and their unique texture.

Minerals

• ​Minerals are the natural, non-living building blocks that make up all rocks.

• ​​They are solids with a specific crystal structure and chemical composition.

• ​Each mineral type has its own unique set of defining properties.

Multiple Choice

What is the fundamental relationship between rocks and minerals?

• Rocks and minerals are both living materials.

• Minerals are made of rocks, and rocks are made of crystals.

• Rocks are the non-living building blocks of minerals.

• Minerals are the non-living building blocks of rocks.

Multiple Choice

How can a rock be distinguished from a mineral?

• A rock has a unique texture, while a mineral does not.

• A rock is made of various mineral grains, while a mineral has a specific chemical composition.

• A rock is naturally formed, while a mineral is man-made.

• A rock is a solid, while a mineral is not.

Multiple Choice

A scientist is examining a sample and observes that it is made of several different types of mineral grains held tightly together. What conclusion can the scientist draw?

• The sample is a rock, because all rocks are made of a single mineral.

• The sample is a mineral, because it has a unique crystal structure.

• The sample is a mineral, because it is a non-living material.

• The sample is a rock, because it is identified by its mineral content.

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Igneous Rocks: Formed from Cooling

Intrusive Rocks

• Forms from magma cooling slowly deep beneath the Earth's surface.

• Slow cooling allows large, easily visible mineral crystals to grow.

• Common examples of these types of rocks include granite and diorite.

Extrusive Rocks

• Forms when lava from a volcano cools rapidly on the surface.

• The quick cooling process results in very small or fine crystals.

• Common examples of these types of rocks include basalt and obsidian.

Multiple Choice

What process is responsible for the formation of all igneous rocks?

• The cooling and solidification of melted rock

• The application of intense heat and pressure to existing rocks

• The layering and cementing of sediment over time

• The weathering and erosion of mountains into small particles

Multiple Choice

What is the key difference in the formation of intrusive versus extrusive igneous rocks?

• Intrusive rocks have small mineral crystals, while extrusive rocks have large mineral crystals.

• Intrusive rocks are found in volcanoes, while extrusive rocks are found deep within the Earth.

• Intrusive rocks cool slowly beneath the surface, while extrusive rocks cool rapidly on the surface.

• Intrusive rocks are formed from lava, while extrusive rocks are formed from magma.

Multiple Choice

A geologist finds an igneous rock with very large, easily visible mineral crystals. What is the most logical conclusion about how this rock formed?

• It was created on the surface from fine particles of volcanic ash.

• It is an example of obsidian, which cooled instantly to form a glassy texture.

• It formed from lava that cooled very quickly after a volcanic eruption.

• It formed from magma that cooled slowly deep beneath the Earth's surface.

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What Are Sedimentary Rocks?

• They are formed from sediments like pieces of rock, shells, or plants.

• Weathering, erosion, and deposition create layers of sediment over long periods.

• Compaction and cementation squeeze and glue these sediments together into solid rock.

• They often have layers and may contain fossils of ancient life.

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Multiple Choice

What are sedimentary rocks primarily formed from?

• Gases that have been trapped underground

• Layers of sediments like rock pieces, shells, or plants

• Existing rocks changed by heat and pressure

• Molten rock that has cooled and hardened

Multiple Choice

How do layers of sediment become solid sedimentary rock?

• They are melted by the Earth's heat and then cool down slowly.

• They are mixed with lava and magma deep within the Earth.

• They are squeezed and glued together by compaction and cementation.

• They are broken down into smaller pieces by weathering and erosion.

Multiple Choice

A scientist discovers a rock that has distinct, flat layers and contains the fossil of a fish. What is the most logical conclusion about this rock?

• It was formed from the cooling of molten lava.

• It is an old rock, but its type cannot be identified.

• It was created by a volcanic eruption near an ocean.

• It is a sedimentary rock formed from deposited sediments.

Metamorphic Rocks: Changed by Heat and Pressure

• Metamorphic rocks are formed by intense heat and pressure.

• The original rock is squeezed, folded, and changed without melting.

• This process can give rocks a striped or banded look.

Multiple Choice

What two things are required to form metamorphic rocks?

• Heat and pressure

• Melting and cooling

• Weathering and erosion

• Compaction and cementation

Multiple Choice

Which statement best describes what happens to a rock as it undergoes metamorphism?

• The rock is squeezed and folded, changing its structure without melting.

• The rock is dissolved by water and then reforms in a new place.

• The rock is broken down into small pieces and carried away by wind.

• The rock melts completely into magma and then cools.

Multiple Choice

A geologist discovers a rock that has a distinct striped and banded appearance. What can the geologist most likely conclude about how this rock was formed?

• It formed from lava that cooled very quickly on the surface.

• It is made of sand and pebbles that were cemented together.

• It was changed by intense squeezing and high temperatures.

• It was created by the evaporation of ancient seawater.

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The Rock Cycle

• The rock cycle is a continuous process that changes rocks from one type to another.

• Igneous rocks form when hot magma or lava cools down and hardens.

• Sedimentary rocks are made from layers of sediment compacted and cemented together.

• Metamorphic rocks are formed when other rocks are changed by heat and pressure.

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Multiple Choice

What is the rock cycle?

• A continuous process that changes rocks from one type to another

• A process that only creates rocks deep inside the Earth

• A collection of different types of rocks in one area

• A process where rocks are broken down into soil

Multiple Choice

How is the formation of sedimentary rock different from the formation of metamorphic rock?

• Sedimentary rock is changed by heat, while metamorphic rock is formed from cooled lava.

• Sedimentary rock is made of compacted sediment, while metamorphic rock is changed by heat and pressure.

• Sedimentary rock is formed from magma, while metamorphic rock is made of layers of sediment.

• Sedimentary rock is changed by pressure, while metamorphic rock is formed from cemented layers.

Multiple Choice

A volcano erupts, and its lava cools to form a rock on the surface. Over millions of years, this rock is broken down into small pieces that settle in a lake and are pressed together to form a new rock. Which two rock types are described as forming in this sequence?

• Igneous, then Metamorphic

• Sedimentary, then Igneous

• Igneous, then Sedimentary

• Metamorphic, then Sedimentary

Uses of Different Rock Types

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Igneous Rocks

• Their interlocking mineral crystals make them very strong and durable.

• They are used to create long-lasting monuments and impressive statues.

• These rocks also serve as strong materials for constructing buildings.

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Sedimentary Rocks

• A type called limestone is a key ingredient for making cement.

• Limestone is also the primary material used to manufacture chalk.

• Shale, another sedimentary rock, is commonly used to make bricks.

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Metamorphic Rocks

• These rocks are valued for use in both art and construction.

• Slate, a common type, is frequently used for roofing on houses.

• Crushed slate is also used to create ballasts for railroad tracks.

Multiple Choice

What property of igneous rocks, resulting from their interlocking mineral crystals, makes them suitable for constructing buildings and monuments?

• Their light weight and porous nature

• Their capacity to absorb large amounts of water

• Their strength and durability

• Their softness and ability to be easily molded

Multiple Choice

Which statement correctly compares the uses of two different sedimentary rocks?

• Both limestone and shale are prized for their strength in building statues.

• Limestone is used for roofing, while shale is used for monuments.

• Limestone is used to make chalk and cement, while shale is used to make bricks.

• Shale is used to make chalk, while limestone is used for railroad ballast.

Multiple Choice

A construction firm needs to source materials to install a new roof on a house and to create ballast for nearby railroad tracks. Which of the following provides the best recommendation?

• Use limestone for the roof and shale for the railroad tracks.

• Use igneous rock for the roof and limestone for the railroad tracks.

• Use slate for the roof and crushed slate for the railroad tracks.

• Use shale for the roof and igneous rock for the railroad tracks.

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Common Misconceptions About Rocks

Misconception	Correction
Rocks are permanent and never change.	Rocks constantly change from one form to another in the rock cycle.
The rock cycle has a set starting and ending point.	The rock cycle is a continuous process with no true beginning or end.
Magma and lava are the same thing.	Magma is molten rock underground; lava is molten rock on the surface.
Sedimentary rocks are rare.	They are common, covering about 75% of the Earth’s land surface.

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Summary

• Rocks are made of minerals and are classified as igneous, sedimentary, or metamorphic.

• Igneous rocks form from cooling lava; sedimentary rocks form from layered sediments.

• Metamorphic rocks are created when other rocks change due to heat and pressure.

• The rock cycle continuously transforms rocks, and each type has important uses.

Poll

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