Minerals

Minerals

Middle School

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Learning Objectives

• Define a mineral and describe the physical properties used for identification.

• Explain how melting, crystallization, and deformation form and alter minerals.

• Connect geoscience processes to the uneven distribution of mineral resources.

• Explain why minerals are limited and non-renewable resources.

Key Vocabulary

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Mineral

A naturally occurring, inorganic solid with a crystal structure and a definite chemical composition.

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Crystal Structure

The repeating pattern of a mineral's particles that forms a solid, creating its unique crystal shape.

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Luster

This describes how light reflects from a mineral's surface, like having a metallic or glassy appearance.

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Streak

The color of a mineral's powder left behind when it's rubbed on a surface, used for identification.

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Cleavage

A mineral's ability to split apart easily and smoothly along flat surfaces, creating reflective sides.

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Fracture

Describes how a mineral looks when it breaks apart in an irregular, uneven, or curved way.

Key Vocabulary

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Mohs Hardness Scale

A 1-10 scale that is used for ranking the relative hardness of different types of minerals.

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Crystallization

The natural process where atoms arrange themselves to form a material with a crystal structure.

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Deformation

The process of changing a rock's original shape by applying immense heat, pressure, or stress.

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Weathering

The natural process of breaking down large rocks and minerals on the Earth's surface into smaller pieces.

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Sedimentation

The geological process of settling or depositing of sediments, often in layers, in a new location.

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Non-Renewable Resource

A natural resource that cannot be replaced by natural means at a pace equal to its consumption.

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What is a Mineral?

• A substance must be naturally occurring, not created by humans.

• It must be a solid, with a definite volume and shape.

• It must be formed by inorganic processes, not from living things.

• The atoms inside it must form an orderly, repeating crystal structure.

• It must have a definite chemical composition, like a fixed recipe.

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Multiple Choice

Which statement best describes the primary characteristics of a mineral?

• It is a man-made solid with a random atomic structure.

• It is a naturally occurring solid with a specific crystal structure and chemical composition.

• It is a liquid substance formed from once-living organisms.

• It can be any natural substance, regardless of its shape or how it formed.

Multiple Choice

Why is coal, which is formed from ancient plant matter, not considered a mineral?

• Because it is not a solid substance.

• Because it does not have a definite chemical composition.

• Because it is formed from organic processes.

• Because it is not naturally occurring on Earth.

Multiple Choice

A scientist creates a new substance in a lab. It is a solid, has a repeating crystal structure, and a fixed chemical recipe. Why would this substance fail to be classified as a mineral?

• Because it does not have a definite volume and shape.

• Because it was not formed by a natural process.

• Because its atoms do not form an orderly structure.

• Because it was not formed from a living thing.

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Identifying Mineral Properties

• Luster describes how light reflects from a mineral’s surface, like metallic or glassy.

• Hardness is ranked on the Mohs scale from 1 (softest) to 10 (hardest).

• Streak is the color of a mineral’s powder and is a reliable identifier.

• Cleavage is a smooth break, while fracture is an irregular or uneven break.

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Multiple Choice

What is the main purpose of testing a mineral's luster, hardness, streak, and cleavage?

• To identify the mineral

• To determine its monetary value

• To find out its age

• To see if it is magnetic

Multiple Choice

How are hardness and cleavage used to describe a mineral?

• Hardness ranks resistance to scratching, while cleavage describes how it breaks.

• Hardness describes the mineral's powder, while cleavage is its shine.

• Hardness is how it breaks, while cleavage is its resistance to scratching.

• Hardness is its shininess, while cleavage is the color of its powder.

Multiple Choice

A student observes a mineral that has a glassy shine and leaves a colored powder when scratched on a plate. Which two properties are being described?

• Luster and Streak

• Hardness and Fracture

• Cleavage and Luster

• Streak and Hardness

How Minerals Form

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From Magma and Lava

• Molten rock cools down, leading to the crystallization of new minerals.

• Magma, cooling slowly underground, forms large, well-defined mineral crystals.

• Lava cools quickly on the Earth's surface, resulting in smaller crystals.

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From Solutions

• Minerals can also crystallize from elements that are dissolved in water.

• When the water evaporates, it leaves behind these elements to crystallize.

• A common example of this process is the formation of halite.

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From Heat and Pressure

• Intense heat and pressure deep inside Earth can change existing minerals.

• This process alters the mineral's internal arrangement of its atoms.

• For example, graphite can be transformed into a diamond this way.

Multiple Choice

What are the primary ways that new minerals can be formed?

• From the cooling of molten rock, the evaporation of solutions, or through heat and pressure.

• Only from the eruption of volcanoes on the Earth's surface.

• Only from the evaporation of water in oceans and lakes.

• From the breaking down of large rocks into smaller sediments.

Multiple Choice

What is the relationship between the cooling rate of magma or lava and the size of the mineral crystals that form?

• The slower the molten rock cools, the larger the mineral crystals will be.

• The faster the molten rock cools, the larger the mineral crystals will be.

• The cooling speed of molten rock does not affect the size of the crystals.

• The location of the cooling, not the speed, determines the crystal size.

Multiple Choice

A scientist is studying a halite crystal and a diamond. What conclusion can be drawn about their formation based on the processes described?

• The halite formed from dissolved elements in water, while the diamond formed from an existing mineral being changed.

• The diamond formed from quickly cooled lava, while the halite formed from slowly cooled magma.

• The halite was created by intense pressure, while the diamond was created by evaporation.

• The diamond is an example of a mineral formed from a solution, while halite is not.

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Uneven Mineral Distribution

• Minerals are not spread out evenly across the planet's surface.

• ​Their formation depends on specific geoscience processes in certain locations.

• Plate tectonics, like at subduction zones, drives these mineral-forming processes.

• This activity helps concentrate elements to form rich metal ores.

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Multiple Choice

Which statement best explains why minerals are not distributed evenly across the Earth's surface?

• Their formation is dependent on specific geoscience processes that happen in certain locations.

• They are spread out evenly, but are difficult to find.

• They are created when rocks are weathered by wind and rain.

• They are distributed based on the planet's rotation.

Multiple Choice

What is the role of plate tectonics in the distribution of minerals?

• It breaks down minerals, scattering them across the surface.

• It drives processes that concentrate elements into rich metal ores.

• It ensures that all locations get an equal share of minerals.

• It only forms minerals deep within the Earth's core.

Multiple Choice

A mining company wants to search for a new, rich deposit of metal ore. Based on the information about mineral formation, which type of location would be the most logical place to start their search?

• A large, flat plain far from any plate boundaries.

• The bottom of the deep ocean, away from volcanic activity.

• An area near a subduction zone where tectonic plates are colliding.

• A desert environment where wind erosion is common.

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Minerals as a Limited Resource

• Many minerals are non-renewable, used much faster than they are naturally replaced.

• ​The geological processes that form minerals often take millions of years to occur.

• Because of this, the mineral resources available for our use are limited.

• Human mining permanently changes the distribution of these finite resources on Earth.

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Multiple Choice

What is the primary reason that many minerals are considered a limited, non-renewable resource?

• They are used by people much more quickly than they are formed.

• They are only located in hard-to-reach places on Earth.

• They are very expensive to extract from the ground.

• They can only be created by human activities in a lab.

Multiple Choice

What is the relationship between the geological process of mineral formation and the availability of minerals?

• The extremely slow geological processes that create minerals cannot keep up with the rate of human use.

• The millions of years it takes to form minerals makes them stronger and more useful.

• The geological processes that form minerals happen so slowly that they are difficult to observe.

• The time it takes for minerals to form ensures they are spread evenly across the planet.

Multiple Choice

If humans continue to mine and use minerals at a high rate, what is the most likely long-term outcome?

• The total global supply of these minerals will permanently decrease.

• Geological processes will speed up to create new minerals faster.

• Humans will find ways to create new minerals to replace the old ones.

• The minerals will eventually be redistributed back to their original locations.

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Common Misconceptions

Misconception	Correction
All rocks are minerals.	Rocks are made of one or more different minerals.
A mineral's color is the best way to identify it.	Streak, hardness, and cleavage are more reliable for identification.
We can always find or make more minerals.	Most minerals are non-renewable and form over millions of years.
Man-made gems are minerals.	A substance must be naturally occurring to be a true mineral.

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Summary

• A mineral is a natural solid with a crystal structure and chemical composition.

• Properties like luster, streak, and hardness are used to identify different minerals.

• Earth's internal heat drives the formation of minerals through melting and crystallization.

• Slow cooling of magma forms large crystals, while fast cooling forms small crystals.

• Geoscience processes, like volcanic activity, lead to the uneven distribution of mineral ores.

• Minerals are considered non-renewable because they form over very long geological timescales.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1 (Not Confident)

• 2 (A Little Confident)

• 3 (Mostly Confident)

• 4 (Very Confident)