1. Minerals
Lecture #5

2. Characteristics of Minerals
Naturally occurring, inorganic (formed from nonliving matter) solid with a crystal structure
Building blocks of rocks
Rock – combination of minerals

3. Minerals Seven Properties Color Crystal Form Luster Streak Cleavage
Fracture
Hardness

4. Color and Clarity Color Clarity Pyrite – fools gold
Transparent – clear
Translucent – foggy
Opaque - solid

5. Crystal Structure Number of sides the mineral has Geometric shapes
Cube
Pyramid
Prism

6. Luster – appearance of mineral in reflective light
Metallic
Looks like medal, leaves dark streak
Nonmetallic
Leaves light streak

7. Streak – color of a minerals powder
True color
Find the color by rubbing the mineral against a piece of unglazed porcelain tile
The color of the mineral and its streak are often different

8. Cleavage and Fracture Break on surface Cleavage
Excellent, good, poor, or absent
Cleavage
Breaks easily along a flat surface

9. Conchodial fracture – bowl shape
Breaks in an irregular way, curved shapes jagged points
Conchodial fracture – bowl shape

10. Hardness Resistance to scratching Can be determined by a scratch test
scratch glass
Soft
No scratch on glass

11. Mohs Scale of Hardness

12. Special properties Calcite Magnetite Halite Reaction to Acid HCl
Magnetic
Halite
salty

13. Graphite
Writes on paper
Gypsum
Soapy feel

14. Plagioclase Feldspar Striations (series of parallel lines)