(4) Minerals

• Rocks

  • naturally occurring AGGREGATE of minerals
• Petrology

  • study of rocks
• Minerals

  • naturally occurring through geological processes
  • have a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties
  • range in composition from pure elements and simple salts to very complex silicates with thousands of known forms
• Mineralogy

  • study of minerals
• Gem

  • cut and polished solid used in jewelry and ornaments
• Sapphire and Ruby

  • gemstones made of the mineral corundum
• Color

  • first impression
  • not very reliable
• Streak

  • TRUE color of a mineral
  • color of a mineral's powder
• Why don't minerals with a hardness greater than 7 create a streak on the streak plate?

  Because they are harder than the porcelain tile
• Hardness

  • mineral's resistance to being scratched
  • depends on how "tightly-packed" the atoms are
• Cleavage

  • splits along definite planes
  • means "to split"
• Fracture

  • breaks irregularly
  • jagged edges
• Luster

  • how light shines off a mineral
  • metallic or nonmetallic
• Density

  • ratio of an object's mass to its volume
• Special Properties of Minerals

  • Magnetism
  • Double Refraction
  • Fluorescence
  • Phosphorescence
  • Piezoelectric
  • Acid Test
• Magnetism

  • attracted to a magnet
  • contains iron, cobalt, or nickel
• Double Refraction

  • looking through it, you see "double"
• Fluorescence

  • glows under UV light
• Phosphorescence

  • continues to glow eve after the UV light has been removed
• Piezoelectric

  • electricity is generated from pressure
• Acid Test

  • uses hydrochloric acid
  • tests for carbonate
• Pyrite

  • fool's gold