1. Chapter 3 Section 2

2. Identifying Minerals
If you closed your eyes and tasted different foods, you could probably determine what the foods are by noting properties such as saltiness or sweetness.
You can also determine the identity of a mineral by noting different properties.

3. Identify seven ways to determine the identity of minerals.
What You Will Learn
Identify seven ways to determine the identity of minerals.
Explain special properties of minerals.

4. Color The same mineral can come in a variety of colors.
For example, in its purest state quartz is clear. Samples of quartz that contain various types of and various amounts of impurities, however, can be a variety of colors.

5. Color
Besides impurities, other factors can change the appearance of minerals.
The mineral pyrite, often called fool’s gold, normally has a golden color. But if pyrite is exposed to air and water for a long period, it can turn brown or black.
Because of factors such as impurities, color usually is not the best way to identify a mineral.

6. Luster The way a surface reflects light is called luster.
When you say an object is shiny or dull, you are describing its luster.
Minerals have metallic, submetallic, or nonmetallic luster.
If a mineral is shiny, it has a metallic luster.
If the mineral is dull, its luster is either submetallic or nonmetallic.

7. Different Types of Luster

8. Streak
The color of a mineral in powdered form is called the mineral’s streak.
A mineral’s streak can be found by rubbing the mineral against a piece of unglazed porcelain called a streak plate.
The mark left on the streak plate is the streak.

9. The streak is a thin layer of powdered mineral.
The color of a mineral’s streak is not always the same as the color of the mineral sample.
Unlike the surface of a mineral sample, the streak is not affected by air or water.
For this reason, using streak is more reliable than using color in identifying a mineral.

11. Cleavage and Fracture
Different types of minerals break in different ways. The way a mineral breaks is determined by the arrangement of its atoms.
Cleavage is the tendency of some minerals to break along smooth, flat surfaces.
Fracture is the tendency of some minerals to break unevenly along curved or irregular surfaces.

12. Clevage

13. Fracture

14. Hardness A mineral’s resistance to being scratched is called hardness.
To determine the hardness of minerals, scientists use Mohs hardness scale, shown in Figure 5.
Notice that talc has a rating of 1 and diamond has a rating of 10.

15. Hardness (continued)
The greater a mineral’s resistance to being scratched is, the higher the mineral’s rating is.
To identify a mineral by using Mohs scale, try to scratch the surface of a mineral with the edge of one of the 10 reference minerals.
If the reference mineral scratches your mineral, the reference mineral is harder than your mineral.

17. Density
Density is the measure of how much matter is in a given amount of space. In other words, density is a ratio of an object’s mass to its volume
The ratio of an object’s density to the density of water is called the object’s specific gravity.

18. Special Properties
Some properties are particular to only a few types of minerals.
The properties shown in Figure 6 can help you quickly identify the minerals shown.
To identify some properties, however, you will need specialized equipment.

22. Types of Diagram

23. Types of Diagrams

24. Luster
Minerals
Metallic
ERJ JC
Nonmetallic
LOVE