1. Unit 9 Lesson 1 What Are Minerals?
Copyright © Houghton Mifflin Harcourt Publishing Company

2. Unit 9 Lesson 1 What Are Minerals?
A mineral is any nonliving solid that has a crystal form.
All minerals form in nature.
There are more than 4,700 different kinds of minerals found on Earth.
Copyright © Houghton Mifflin Harcourt Publishing Company

3. Unit 9 Lesson 1 What Are Minerals?
Mineral crystals come in different shapes, but all particles in a crystal combine to form a shape that is repeated.
The repeating structure of the particles forms the mineral crystal.
A mineral is always made up of the same set of nonliving elements.
Copyright © Houghton Mifflin Harcourt Publishing Company

4. Unit 9 Lesson 1 What Are Minerals?
Which Mineral Is Which?
Hardness is one property used to identify minerals.
Hardness is the ability of one mineral to scratch another mineral.
The Mohs scale is used to describe the hardness of a mineral. The softest minerals score 1 and the hardest minerals score 10.
Copyright © Houghton Mifflin Harcourt Publishing Company

5. Unit 9 Lesson 1 What Are Minerals?
Which Mineral Is Which?
Luster is another property used to identify minerals. It describes how minerals reflect light.
The minerals copper, gold, and silver have a metallic luster.
Talc and gypsum have an earthy luster. Some minerals have a glassy luster.
Copyright © Houghton Mifflin Harcourt Publishing Company

6. Unique Properties of Minerals
Unit 9 Lesson 1 What Are Minerals?
Unique Properties of Minerals
The way a mineral breaks can also be used to identify it.
When minerals break, the broken sides are smooth and straight. Minerals that break this way have cleavage.
Minerals that do not break along smooth lines have fracture.
Copyright © Houghton Mifflin Harcourt Publishing Company

7. Unique Properties of Minerals
Unit 9 Lesson 1 What Are Minerals?
Unique Properties of Minerals
The color of a mineral’s streak can also be used to identify it.
Streak is the color of a mineral when it is rubbed against a white tile.
A streak can be the same color as the mineral itself. This is not true for many minerals. Pyrite has a gold color, but its streak is greenish-black.
Copyright © Houghton Mifflin Harcourt Publishing Company

8. Unique Properties of Minerals
Unit 9 Lesson 1 What Are Minerals?
Unique Properties of Minerals
A mineral can come in different colors, such as corundum crystals. However the streaks of these crystals are always white.
Some minerals have other properties that can be used to identify them.
For example, calcite and fluorite glow under a black light. Calcite fizzes when you drop vinegar on it. Quartz conducts electricity.
Copyright © Houghton Mifflin Harcourt Publishing Company