Chapter 4: Section1What Are Minerals?

Minerals – a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition

What 5 Characteristics Does a Mineral Have to

Have?A mineral must be: Naturally Occurring Inorganic Solid Crystal Structure Definite Chemical

Composition

What Does It Mean to Be Naturally Occurring?

A mineral must occur naturally

Cement, brick, steel, and glass all come from substances found in Earth’s crust but they are manufactured by people

How Can Something Be Inorganic?

Inorganic – the mineral cannot arise from materials that were once part of a living thing

Ex. Coal is NOT a mineral because it is made up the remains of plants and animals

What kind of pattern must a mineral have?

A mineral must have a crystal structure – a repeating pattern of a mineral’s particles that forms a solid.

Faces – a crystal’s flat side that meets at sharp edges and corners

What kind of composition must a

mineral have?A mineral must have a definite chemical composition – it always contains certain elements in definite proportions; most minerals are compounds

Cinnabar – composed of the

elements Mercury and

Sulfur

What Is the Difference Between an Element and a Compound?

Element – a substance composed of a single kind of atom. Ex. Hydrogen

Compound – Two or more elements combined so that the elements no longer have distinct properties Ex. Water H20

How Do You Identify Minerals?

Properties:DensityCrystal Shape

Cleavage and Fracture

Special Properties

HardnessColor (this can vary)

StreakLuster

How Do You Determine a Mineral’s Hardness?

Friedrich Mohs invented a test to describe and compare the hardness of minerals

Mohs Hardness ScaleRanks ten minerals from softest to hardest

How Does the Mohs Scale Work?

Gypsum (2) will scratch talc (1), calcite (3) will scratch gypsum (2), fluorite (4) will scratch calcite (3), etc.

What Is a Streak Test?The streak of a mineral is the color of its powder

The streak color and the mineral color are often different

To test: rub a mineral against an unglazed tile (streak plate)

What is the Luster of a mineral?

Luster – used to describe how a mineral reflects light from its surface

Minerals containing metals are often shiny

Earthy, waxy, and pearly

What does Density have to do with Minerals?

Each mineral has a characteristic Density

Density – or mass per unit volume; Density = mass/volume

Displacement – the volume of the displaced water equals the volume of the the sample

What Kind of Shape does a Mineral have?

Minerals have a crystal structureCubicHexagonalTetragonalOrthorhombicMonoclinicTriclinic

What is Mineral Cleavage? Cleavage – A

mineral’s ability to split easily along a flat surface

The ability to break apart depends on the arrangement of the atoms in the mineral

Cubic Cleavage

Basal Cleavage

What is Mineral Fracture?

Fracture – How a mineral looks when it breaks apart in an irregular way

What Special Properties does a Mineral have?

Fluorescence –minerals that glow under ultraviolet light

Magnetism - ex. LoadstoneChemical Reactivity- ex. Calcite gives off carbon dioxide

Electrical Properties – ex. quartz

Section2: How are Minerals Formed?

Two General Ways: Crystallization of melted materials

Minerals from Magma Crystallization of materials dissolved

in waterMinerals from Hot water solutions

Minerals formed by evaporation

What is Crystallization?

Crystallization the process by which atoms are arranged to form a material with a crystal structure

How do Minerals form from Magma?

Minerals form as magma cools inside the crust, or as lava hardens on the surface

What Effects Crystal Size?Rate at which magma

coolsSlower cooling forms larger crystals

The amount of gas the magma contains

The chemical composition of the magma

How do Minerals Form from Hot Water Solutions?

Magma beneath Earth’s surface has heated the water to a high temperature beneath Earth’s surface causing minerals to dissolve

When this solution cools the elements and compounds leave the solution and crystallize as minerals

What is a Solution?

Solution – A mixture in which one substance dissolves in another

What do Pure Metals often form from Hot Water

Solutions? Veins – A narrow channel or slab of

a mineral that is much different from the surrounding rock

How are Minerals Formed by Evaporation?

As water turns to vapor it leaves behind the mineral

Example: A salt water solution leaves behind large crystals of salt

Where are Minerals Found?

Earth’s crust is made up of a variety of minerals however; rare and less common minerals are usually located near plate boundaries because of volcanic activity and mountain building

Section 3: How are Minerals Used?

Minerals are the source ofMetals ex. Aluminum, Iron

Gemstones ex. Rubies and Sapphires

Other Useful materials ex. Talc (talcum powder)

Ore What?Ore - A rock that contains a metal or economically useful mineral

Most metals, gemstones, and useful minerals must be separated from their ores

What are the 3 Types of Mines?

Strip Mines – Giant equipment is used to scrape away soil

Open Pit Mines – Miners dig a tremendous pit

Shaft Mines – A network of tunnels that extend deep underground