Field Trip #1: Hocking Hills State ParkSaturday, October 2nd

MINERALS: The Building Blocks of Rocks

Definition of a Mineral

• A Mineral is a naturally occurring, inorganic, solid, crystalline substance, with definite physical and chemical properties.

• Inorganic – not composed of Carbon – Hydrogen molecules (usually part of living tissue)

• Crystalline – atoms have a structured arrangement.

CRYSTAL SHAPES

How Do Crystals Form?Remember Atomic Structure

ATOMS DO NOT WANT TO BE NEUTRAL THEY WANT TO BE STABLE

Stable Means Having Their Outer Shell Of Electrons Full To Capacity

This Can Happen By Losing Or Gaining Electrons to Other Atoms

This Process causes Atoms to Join Together: A Process Called Bonding

1) IONIC BONDING

2) COVALENT BONDING

OTHER BONDS3) Metallic – Electrons act as a mobile cloud that moves from atom to atom. Accounts for

excellent electrical conductivity of metals Example: Copper

4) van der Waals – Very weak Bond due to slight polarity of charge on atoms

MINERAL PROPERTIES: HARDNESS

MINERAL PROPERTIES: CLEAVAGEBreakage along planes of crystal weakness

MINERAL PROPERTIES: Other PropertiesColorStreak – color of powdered mineral Luster – the way light reflects of a mineralSpecific Gravity – Weight of Mineral

Weight of same volume of water

Fracture – breakage through crystalReactivity – Reacts with Acid?

MAJOR MINERAL GROUPSWhat are the most common minerals in the Crust?

1) What are the most common elements?

1) SILICATES – Made From Silicon + Oxygen> 91% of all crustal minerals

The Silicon – Oxygen Tetrahedron

The Silicon – Oxygen Tetrahedron can bond together in many different ways producing many different minerals

Other Important Mineral Groups

2) Carbonates – based on Carbonate ion (CO3) Calcite - Ca CO3, Dolomite - CaMg (CO3)2

Main component of the rocks limestone & dolostone.

3) Oxides – usually metals + oxygen Hematite - Fe2O3 (Iron Oxide or Rust), Corundum - Al2O3 (Aluminum Oxide or Ruby). Excellent source of ore metals

Other Important Mineral Groups

4) Sulfides – based on sulfide ion (S2-) Pyrite - FeS2 (“Fool’s Gold”) Excellent source of ore metals

5) Sulfates – based on sulfate ion (SO4)-

Gypsum - CaSO4 (Drywall) Used in the construction industry

So, why study minerals?1) Building Blocks of Rocks – what the Earth is made of.2) Important Economically – Industry & Agriculture.3) Can be incredibly beautiful!!