What is a Mineral

Chapter 3 Minerals of Earth’s Crust

Mineral

• A naturally formed, inorganic solid that has a definite crystalline structure

Questions to ask yourself

• Is it a nonliving material?– A mineral is inorganic, meaning it isn’t made of living things

• Is it a solid– Minerals cant be gases or liquids

• Does it have a crystalline structure– Minerals are crystals, which have a repeating inner structure that

is often reflected in the shape of a crystal. Minerals generally have the same chemical composition throughout

• Is it formed in nature?– Crystalline materials made by people aren’t classified as

minerals.

What is an

• Pure substance that cannot be broken down.

What is a Compound made of?

• Compound- a substance made of TWO or more elements that have been CHEMICALLY combined.– Ex: Halite (NaCl)

Crystals • A solid whose atoms, ions, or

molecules are arranged in a definite pattern – Geometric forms of minerals produced by

a repeating pattern of atoms– Shape is determined by arrangement of

atoms

Two Groups of Minerals

• Most common classification of minerals is based on chemical composition.– Silicate Minerals – Nonsilicate Minerals

Silicate Minerals

• Minerals that contain a combination of silicon and oxygen as well as other elements.

• Make up more than 90% of the Earth’s crust

• Other common elements they combine with include: aluminum, iron, magnesium and potassium.

Common Silicate Minerals

Quartz

Feldspar

Mica

Nonsilicate Minerals

• Minerals that do not contain a combination of the elements silicon and oxygen.

• Some include carbon, oxygen, fluorine, and sulfur.

• Classes of nonsilicate minerals:– Native Elements – Carbonates– Halides – Oxides – Sulfates – Sulfides

HaliteSpinel Gypsum

GalenaPyrite Calcite

Hematite

Native Elements

• Minerals composed of only one element– Ex: copper, gold, silver – Used in communications and electronic

equipment

Carbonates

• Minerals that contain combinations of carbon and oxygen in their chemical structure.

• Used in cement, building stones and fireworks

Halides• Compounds that form when fluorine,

chlorine, iodine, or bromine combine with sodium potassium or calcium.

• Used in the chemical industry and in detergents

Oxides

• Compounds that form when an element such as aluminum or iron combines chemically with oxygen.

• Used to make abrasives, aircraft parts and paint

Sulfates

• Minerals that contain sulfur and oxygen

• Used in cosmetics, toothpaste, cement, and paint.

Sulfides• Minerals that contain one

or more elements, such as lead, iron or nickel, combined with sulfur.

• Used to make batteries, medicines, and electronic parts.

Assignment

• Section Review Chapter 3 Section 1

Identifying Minerals

• We use several different properties to help identify minerals– Color– Luster– Streak– Cleavage and Fracture– Hardness– Density– Special Properties

Color

• The same mineral can often come in a variety of colors

• Not the best way to identify a mineral

All 3 are Pyrite (fools gold)

Luster

• The way a surface reflects light

• Minerals have metallic, submetallic or nonmetallic luster– Shiny = metallic– Dull = submetallic or nonmetallic

Types of Mineral Luster

Bright and Reflective

Dull and Reflective

Dull and Plastic

Streak

• Color of a mineral in powdered form

• Found by rubbing the mineral against a piece of unglazed porcelain called a streak plate

• The color of the mineral’s streak is not always the same as the color of the mineral sample

• Good way to identify a mineral

Cleavage• The splitting of

a mineral along smooth, flat surfaces.

Fracture

Different types of minerals break in different ways. The way a mineral breaks is determined by the arrangement of its atoms.

The manner in which a mineral breaks along either curved or irregular surfaces

Hardness

• A minerals resistance to being scratched

• We use Mohhs Hardness scale to determine the hardness

• To identify a mineral scratch the surface of a mineral with the edge of one of the 10 reference minerals.

• If it scratches the reference mineral your mineral is harder

Mohs Hardnes Scale

Density • Measure of how much matter is in a given

object

• Ratio of an objects mass to it’s volume

• Measured in grams per cubic centimeter

• Water is used as a reference because we know it has a density of 1g/cm3

Special Properties

• Some properties are particular to only a few types of minerals.

Assignment

• Section Review 3-2 page 73 #1-8