1. Special Properties of Minerals
Magnetism Feel
Taste Smell
Optical Properties

2. Magnetism
Magnetite
Lodestone – natural compass

3. Feel
Graphite feels greasy
Talc feels soapy

4. Taste Halite is rock salt, so it tastes salty.
Halite is not always cube-shaped, but it always tastes salty.

5. Smell
Sulfur – smells like match heads

6. Special Properties
Striations
Tourmaline

7. Striations on Pyrite Crystals

8. Striations usually run lengthwise…
Imperial Topaz

9. Striations on Quartz run crosswise rather than lengthwise.

10. Iridescence Optical Properties
The mixing of reflected light rays is called interference.
Constructive Interference - wavelengths of light are in phase and are strengthened
(amplified)
Destructive Interference - wavelengths of light are out of phase and are cancelled out

11. Optical Properties Iridescent Soap Bubbles Thin film = magenta color
Thick film = blue color

12. Iridescence Optical Properties Chalcopyrite ”Peacock Ore”
Labradorite ”Schiller”
(Internal Iridescence)

13. Optical Properties
Iridescence
Opal ”Opalescence”

14. “Cats Eye”
“Tiger Eye”

15. Star Sapphire
Star Ruby
Golden Star Sapphire

16. Optical Properties Total Internal Reflection Optic Fibers
Fiber Optic Cable

17. Optical Properties Total Internal Reflection Optic Fibers
Needle-like Ulexite Crystals

18. Optical Properties Total Internal Reflection in Ulexite - the
“TV Rock”

19. Optical Properties
Polarized Light

20. Optical Properties Double Refraction Iceland Spar
Calcite creates a double image

21. Optical Properties
Iceland Spar Polarizes Light:

22. Optical Properties
Double Refraction
Iceland Spar Calcite

23. Viewed through Crossed Polarizers
Rock Thin Sections
White Light
Viewed through Crossed Polarizers

24. Crossed Polarizers make crystals of different minerals easier to tell apart:

25. Polarized filters enhance photos..
Optical Properties
Polarized filters enhance photos..

26. Optical Properties
The sky is polarized.

27. Optical Properties
Fluorescence

29. Iridescence Optical Properties Orange light is bright.
Green light is absent.
Constructive Interference (Orange) Enhances Color
Destructive Interference (Green) – Reduces Color