1. Minerals
Chapter 9
Section 1

2. Learning Objectives
Identify the difference between a mineral and a rock
Describe the properties that are used to identify minerals
Each mineral has a set of physical properties that can be used to identify it

3. New Vocabulary
Mineral
Rock
Crystal
Gem
Ore

4. What is a mineral? Where are they found?
Are they in a cave? Or in a mine?
Minerals can be found anywhere and everywhere!
What are some examples of minerals?
Pencils (graphite), salt, metal pots, glassware, ceramic dishes

5. What is a Mineral?
Minerals: inorganic, solid materials found in nature
Inorganic: usually not formed by plants or animals
Minerals often have a beautiful crystal shape
The particular chemical makeup and arrangement of the atoms in the crystal is unique to each mineral
Rocks: usually made of two or more minerals

6. Minerals
Each mineral has a unique characteristics that is used to identify it
Over 4,000 minerals have been identified so far

7. How do minerals form? There are several ways minerals form:
Melted rock material in Earth (Magma)
As it cools, atoms combine in orderly patterns to form minerals
Also form as magma reaches Earth’s surface (lava)

8. How do Minerals form? 2. Evaporation forms minerals
Salt crystals appear when seawater evaporates; other dissolved minerals can crystallize
3. Precipitation can form minerals
Water can hold only so much dissolved material
Extra separates and falls out as solid
To figure out how a mineral was formed, you have to look at the size of the mineral crystal and how the crystals fit together

9. Properties of Minerals
Each mineral has a set of physical properties than can be used to identify it
We will discuss 6 properties of minerals that are helpful in identifying them
Crystals: solid materials that have a repeating pattern of atoms
Pyrite commonly forms crystals with 6 faces

10. Properties of Minerals
Cleavage and Fracture
The way a mineral breaks can help identify it
Splits into pieces with smooth, regular panes that reflect light = cleavage
Minerals that break into pieces that are jagged or have rough edges = fracture

11. Properties of Minerals
3. Color:
Sometimes a minerals color can help figure out what it is
Color can also fool you! (Fool’s gold is pyrite)
The same mineral can occur in a variety of colors
Calcite in figure 5 pg 271

12. Properties of Minerals
4. Streak & Luster
Streak: The color of the powered form of a mineral
If a mineral is rubbed across an unglazed, white tile, (streak plate) it produces a streak of color
Sometimes the streak is different than the color of the mineral
Luster: describes how light reflects off the mineral’s surface
Is it shiny, dull, pearly, glassy, or earthy
Metallic minerals = shiny like a metal
Nonmetallic minerals = pearly, glassy, dull or earthy

13. Properties of Minerals
Hardness
Some minerals are harder than others
Soft ones like talc can be scratched with fingernails
Hard ones like diamonds are so hard they can be used to cut almost anything else
Mohs scale: classifies minerals on a scale of 1 (softest) to 10(hardest)
Use one mineral to scratch another to see which on is harder

14. Properties of Minerals
Specific Gravity
Some minerals are heavier than others
Specific gravity compares the weight of a mineral with the weight of an equal volume of water
Fool’s gold is 5 times heavier than water; real gold is 19 times heavier than water
Easily tell this by holding each in your hand

15. Other Properties
There are other properties that can help identify minerals
Magnetite will attract to a magnet
Calcite will fizz when it comes into contact with acids
Some scientists will taste minerals to identify them (YUCK!!)

16. Common Minerals There are over 4,000 minerals that make up most rocks
“rock-forming minerals”
Most rock-forming minerals are silicates
They contain the elements silicon and oxygen
Quartz is pure silica
Feldspar (type of silicate mineral) makes up ½ rocks
Carbonates are another type of important rock-forming minerals
Made of carbon and oxygen
Calcite is a carbonate

17. Common Minerals
Other common minerals can be found in rocks that formed at the bottom of ancient seas as they evaporated
Gypsum is abundant in many places
Halite or rock salt is found in large quantities in the Midwest

18. Gems Gems are minerals that are rare and can be cut and polished
Must be clear with few or no blemishes or cracks
Must have beautiful luster or color
Very few minerals meet these standards
Gems are very rare and valuable

19. Making A Gem
Gems are rare because they are formed under special conditions
Diamonds are forms of the element carbon
Diamonds can be made in a lab setting or they are formed deep within Earth’s mantle
Volcanic eruptions bring diamonds to the surface for miners to find
Pg 274 figure 9

20. Ores
A mineral is called an ore if it contains enough of a useful substance that it can be sold for profit
Many metals that we use come from ores
Iron used to make steel
Lead used to make batteries
Magnesium in vitamins
Extracted from Earth’s surface by mining

21. Conserving Ores Scrap metal recycled or reused to decrease mining
Ores take millions of years to form so they are considered a non-renewable resource
Mining can disrupt environments, landscapes, use valuable resources and increase production costs

22. Ore Processing
After mining, ore must be processed to extract the desired mineral or element
Copper goes through a process called smelting
After this process, copper can be refined or purified
Then it can be processed into many materials
Sheet metal, electrical wiring, cookware, etc…

23. Review Questions
Explain the difference between a mineral and a rock. What are 5 common rock-forming minerals? (pg 273 for minerals that form rocks)
List 5 properties that are commonly used to identify minerals.
Describe an event that must occur in order for diamond to reach Earth’s surface. Where in Earth is diamond formed?
Would you want to live close to a gold mine? Explain why or why not.