Rocks and minerals

• Rocks

  ✓ a relatively hard, naturally occurring mineral material

  ✓ a natural substance composed of solid crystals of different minerals that have been fused together into a

  solid lump

  ✓ can consist of a single mineral or of several minerals that are either tightly compacted or held together by a

  cementlike mineral matrix
• Mineral

  ✓ a naturally occurring, inorganic solid substance.

  ✓ has a specific chemical composition and atomic structure.

  ✓ typically formed through geological processes over long periods.
• What is the hue of a mineral referred to as?

  Color
• Why is color not always reliable for mineral identification?

  Because it can vary due to impurities and environmental factors
• What does the term 'streak' refer to in mineralogy?

  The color of a mineral's powdered form
• How is streak more consistent than color in mineral identification?

  Streak is less affected by impurities and surface conditions
• What does luster describe in minerals?

  The way light reflects off the surface of a mineral
• Why is luster an important property in identifying minerals?

  It helps distinguish between different minerals based on their reflective qualities
• What is cleavage in the context of minerals?

  The tendency of a mineral to break along specific planes
• What is the result of a mineral's cleavage?

  It produces smooth surfaces when the mineral breaks
• What does fracture refer to in mineralogy?

  The way a mineral breaks when it does not cleave
• What type of surfaces does fracture produce?

  Irregular surfaces
• What is crystal form in relation to minerals?

  The geometric shape in which a mineral naturally occurs
• What does it mean for a mineral to grow without interference?

  It means the mineral can develop its natural geometric shape
• How is hardness measured in minerals?

  On the Mohs scale
• What does the Mohs scale measure?

  The resistance of a mineral to being scratched
• How do the properties of color, streak, and luster differ in mineral identification?

  Color is variable, streak is consistent, and luster describes light reflection
• What are the key physical properties of rocks and minerals?

  • Color: Hue of a mineral, not always reliable
  • Streak: Color of powdered form, more consistent
  • Luster: Light reflection off the surface
  • Cleavage: Breaks along specific planes, smooth surfaces
  • Fracture: Breaks irregularly, producing rough surfaces
  • Crystal form: Geometric shape when grown without interference
  • Hardness: Resistance to scratching, measured on Mohs scale
• Mohs Hardness Scale ranks minerals from 1 (softest) to 10 (hardest).

  o Minerals can be tested for hardness using the scale.

  o Hardness influences a mineral's ability to scratch or be scratched.

  Hardness Mineral

  1 Talc

  2 Gypsum

  3 Calcite

  4 Fluorite

  5 Apatite

  6 Feldspar

  7 Quartz

  8 Topaz

  9 Corundum

  10 diamond
• What is the rock cycle?

  A continuous process of rock formation and transformation on Earth's surface and interior
• How do rocks change from one type to another in the rock cycle?

  Through geological processes such as melting, cooling, weathering, erosion, deposition, heat, and pressure
• What are the three main types of rocks involved in the rock cycle?

  • Igneous
  • Sedimentary
  • Metamorphic
• What initiates the rock cycle?

  The cooling and solidifying of molten magma to form igneous rocks
• What happens to igneous rocks when they are weathered and eroded?

  They turn into sediments, which can become sedimentary rocks through compaction and cementation
• What processes transform sediments into sedimentary rocks?

  Compaction and cementation
• What can happen to both igneous and sedimentary rocks under certain conditions?

  They can be subjected to heat and pressure, causing them to metamorphose into metamorphic rocks
• What is the final step in the rock cycle involving metamorphic rocks?

  Metamorphic rocks can melt and become magma, restarting the cycle
• 2 types of igneous rocks

  intrusive- slow magma cooling

  ex. granite

  extrusive- rapid lava cooling

  ex. obsidian
• Igneous

  • forms from magma or lava solidification
  • hard, no layers
• Sedimentary

  • forms from sediment compaction
  • crumbly, layered
• 3 types of sedimentary

  classic- compacted broken rocks

  ex. sandstone

  Chemical- compacted dissolved minerals

  ex. limestone

  organic- compacted biogenic matter

  ex. coal
• Metamorphic

  • forms by transformation of other rocks
  • relatively hard, may or may not have layers
• 2 types of metamorphic

  foliated- has layers

  ex. slate

  non-foliated- no layers

  ex. marble
• sedimentary processes: erosion, deposition, compaction, cementation
• This is determined by a scratch test...

  hardness
• How a mineral reflects light from its surface...

  luster
• Color of a mineral in powdered form...

  steak
• The three major rock groups include...

  sedimentary, igneous, metamorphic
• The names of the three rock types refer to...

  how they formed
• How a mineral appears (brown, green, etc.)...

  color