1. Properties of Minerals
Geologists use characteristics to tell one mineral from another
Color / Luster / Hardness
Break Patterns / Density / Special Properties

2. I. Color Not a reliable property for identifying minerals
Examples: Quartz – smoky, rose, or amethyst, Fluorite – many colors

3. A mineral can be many different colors. Below is Mica.

4. Many minerals can be the same color. Below are gold colored minerals
Many minerals can be the same color. Below are gold colored minerals. Which one is gold?

5. II. Luster
Refers to the way light reflects from the surface of the mineral.
There are two types of luster,
Metallic: looks like polished metal.
Nonmetallic: does not look like polished metal.
Nonmetallic - Vitreous, Silky, Resinous, Waxy, Pearly, Earthy

6. Pyrite has metallic luster

7. Quartz has nonmetallic luster

8. III. Hardness A minerals resistance to being scratched.
Friedrich Mohs German Mineralogist

9. Gypsum is soft, it can be scratched by a fingernail.

10. Calcite is soft, but a little harder because it cannot be scratched by a fingernail, but it can be scratched by a penny.

11. Fluorite is harder. It can be scratched by a nail, but not a penny or fingernail.

12. Diamonds are the hardest mineral, so it scratches every mineral.

13. IV. Break Patterns Cleaving – When minerals break along flat surfaces
Fracture – Some minerals break unevenly along curved or irregular surfaces
Many types of fracture & cleaving

14. Quartz: Conchoidal Fracture

15. Mica cleaves in one direction. It breaks along one line.

16. Feldspar has two lines of cleavage. It breaks along two lines.

17. V. Streak The color of a minerals powder
Minerals are scratched along a streak plate to create powder
Some minerals powder is a different color from its regular color
Use both black and white plates

18. Gold
When gold is run across a streak plate it makes a yellowish-gold color.
That makes sense.

19. Pyrite or “Fool’s Gold”
When pyrite is run across a streak plate, it has a black or dark green streak.
Pyrite is not worth much money, while gold is worth a lot. They look alike, so miners call it fool’s gold.

20. Hematite Hematite’s color is grey, but its streak is red.
Hema means blood.
The mineral was named hematite because it looked like it was bleeding when it was taken across a streak plate.

21. VI. Density Density of Platinum = 21.45 g/cm^3
Density – how much matter there is in a given amount of space
Density(g/cm^3) = mass(g) / volume (cm^3)
Density of Platinum = g/cm^3

22. VII. Special properties
Fluorescence – glow under ultraviolet light
Optical properties
Chemical reactions
Taste
Magnetism
Radioactivity