1. Properties & Special Properties
Minerals
Properties
&
Special Properties

2. Earth’s Crust Made of Rock Rock is made of minerals (and other stuff)
are naturally made.
are inorganic (non-living)
are solid.
have a definite chemical composition which give it definite crystal shape

3. Earth’s Crust Most abundant elements in Earth’s crust #1 – oxygen
#2 – silicon
#3 – Aluminum
#4 – Iron
#5 – Calcium

4. Mineral Families Silicates – Most Abundant
Must contain silicon and oxygen
SiO2 (quartz)
Carbonates – most often used in building industry (cement, concrete, etc.)
Must contain carbon and oxygen
CaCO3 (calcite)
Halides
Must contain Fluorine, Chlorine, Iodine or Bromine
CaFl2 (fluorite)
Sulfates
Must contain sulfur and oxygen
BaSO4 (barite)

5. Mineral Families (cont.)
Sulfides
Must contain sulfur and a metal (no oxygen)
ZnS2 (pyrite)
Oxides (used to make steel, etc.)
must contain a metal and oxygen
Fe3O4 (magnetite)
Native Elements
One single element
Au (Gold)
C (Diamond)
C (Graphite)

6. Mineral Properties Color Crystal Structure Hardness
Heft/Specific Gravity (density compared to water)
Luster
Break Pattern (Cleavage or Fracture)
Streak
Click below for video clip

7. Property: Color
Not reliable because some minerals have impurities that make one mineral different colors
Example: Quartz
Several minerals can also share the same color
Example: Quartz, Calcite, Halite can all be clear
Amethyst
Rosie Quartz
Milky Quartz
Smokey Quartz

8. Crystal Structure
A repeating pattern of atoms, ions, or molecules that is present throughout a mineral.
Examples – cubic, hexagonal, triclinic

9. Hardness
Moh’s Scale of Hardness
Hardness
Minerals/Gemstones
Test 1
Talc, Sulpher
Scratched w/fingernail 2
Gypsum, Amber (2-3) 3
Calcite, Coral (3-4), Pearl (3-4), Malachite (3.5-4)
Scratched w/copper penny 4
Fluorite, Rhodochrosite
Scratched w/ knife blade easily 5
Apatite, Lapis (5-6), Turquoise (5-6), Opal (5.5-6)
Scratched w/knife blade 6
Feldspars, Moonstone, Tanzanite (6.5-7), Peridot (6.5-7)
Scratched w/steel file 7
Quartz, Tourmaline (7-7.5), Garnet (7-7.5), Beryl (7.5-8)
Scratches glass 8
Topaz, Alexandrite (8-8.5) 9
Corundum 10
Diamond
A mineral’s resistance to being scratched or mechanically broken down
Use Mohs Scale.

10. Hardness of Graphite and Diamond
Graphite (fragile and soft) and diamond (hardest known substance on Earth) are both made of carbon.
Why are they so different?
Internal bonding arrangements of the carbon atoms.

11. Heft/Specific Gravity
Density of a mineral compared to density of water (Water’s density is 1 g/mL)
Or - way of determining the density of a mineral by “feeling” how heavy it feels for its size
Example – the heft of mica is less than magnetite (mica feels “lighter” than magnetite when they are the same size)

12. Luster
How a mineral reflects light – is it shiny or dull…is it glassy or pearly…is it metallic or non-metallic?

13. Break Pattern – Cleavage & Fracture
Cleavage – when broken, the mineral has smooth flat surfaces

14. Break Pattern – Cleavage & Fracture
Fracture – when broken, the mineral has jagged, uneven surfaces

15. Streak
The color of a mineral in powdered form – use an unglazed porcelain plate.
More reliable than the color property
the streak for each type of quartz is the same (clear/white)

16. Special Properties
Smell – sulfur smells like rotten eggs

17. Special Properties
Taste – halite tastes salty (some minerals are poisonous so CAREFUL with this one!
Fluorescence – fluorite glows under UV light

18. Special Properties Magnetism – magnetite attracts metal
Double Refraction (bends light) – calcite

19. Special Properties Reacts with acid – calcite bubbles/fizzes with acid
Feel – talc and graphite feel greasy or slick