1. Properties of Minerals
Chapter 2.3
Mrs. Schwartz

2. Properties of Minerals
Definition of a Mineral:
naturally occurring
inorganic
solid
characteristic crystalline structure
definite chemical composition

3. How can we identify minerals?
Physical properties:
Color
Cleavage
Streak
Fracture
Luster
Density
Hardness
Special Properties (distinctive)
Crystal form

4. Color
LEAST USEFUL PROPERTY, CHANGE IN THE CHEMICAL FORMULA WILL VARY THE COLOR OF THE MINERAL. (QUARTZ) SiO2

5. Streak the color of a mineral in its powdered form.
Obtained by scratching a mineral on a piece of unglazed porcelain.

6. Luster THE WAY A MINERAL SHINES IN REFLECTED LIGHT.
Different kinds of luster:
Metallic
Non-metallic
Waxy
Earthy

7. Luster - Metallic
METALLIC- LOOKS LIKE METAL IN THE WAY THE MINERAL REFLECTS LIGHT (GALENA OR PYRITE)

8. Luster- Non-metallic
NON-METALLIC- DOES NOT LOOK LIKE POLISHED METAL, SO OTHER TERMS ARE USED

9. Other lusters  WAXY- DULL SHINE LIKE CANDLE WAX (SULFUR, OLIVINE)
 EARTHY- NO SHINE AT ALL (BAUXITE)

10. Crystal Form Crystal Form (or shape):
external expression of a mineral’s internal atomic structure
planar surfaces are called crystal faces
angles between crystal faces are constant for any particular mineral

11. Hardness How easy it is to scratch a mineral Mohs Scale of Hardness
relative scale
consists of 10 minerals, ranked 1 (softest) to 10 (hardest)

12. Mohs Scale of Hardness Hardest (10) – Diamond Softest (1) – Talc
Common objects:
- Fingernail (2.5)
- Copper penny (3.5)
- Wire nail (4.5)
- Glass (5.5)
- Streak plate (6.5)

13. Cleavage
the tendency of a mineral to cleave, or break, along flat, even surfaces.

14. Fracture
Minerals that do not show cleavage when broken are said to fracture.
Fracture—the uneven breakage of a mineral

15. Defined as the mass divided by the volume.
Density
Defined as the mass divided by the volume.

16. Special Properties
MAGNETIC – THE ABILITY TO ATTRACT A MAGNET (MAGNETITE)
EFFERVESCENCE – ADDING HCL TO A MINERAL CAUSES IT TO FIZZ
TASTE – HALITE

17. Special Properties
ODOR – SOMETIMES THE POWDER OF A MINERAL HAS A CERTAIN ODOR (SULFUR SMELLS LIKE ROTTEN EGGS)
DOUBLE REFRACTION – SPLITS LIGHT RAYS (CALCITE)

18. Special Properties
FLUORESCENCE – THE ABILITY TO GLOW UNDER ULTRA VIOLET LIGHT (SPHALERITE)
SPECIFIC GRAVITY (DENSITY) – SOME MINERALS HAVE ATOMS VERY TIGHTLY PACKED, AND FEEL HEAVIER BECAUSE THEY ARE MORE DENSE (GALENA)