Minerals and Their Properties

Minerals and Their Characteristics

• Minerals are the building blocks of rocks.
• They are composed of one or more chemical elements.
• Minerals have a definite chemical composition, which can be represented by a chemical formula.
• Atoms in minerals are arranged in an orderly, repeating pattern forming a crystalline structure.
• Minerals are naturally occurring, inorganic solids with a definite volume and rigid shape.

Different Properties of Minerals

• Minerals are distinguished based on different physical and chemical properties.
• Physical properties, like color, streak, hardness, cleavage, and crystalline structure, can be readily observed and used for identification.
• Chemical properties, however, aren't as easily determined.

Properties of Minerals: Specific Details

• Color: A mineral's color can vary depending on the surface.
• Streak: The color of a mineral in powdered form.
• Hardness: A mineral's resistance to being scratched. The Mohs scale of hardness rates minerals from 1 (softest - talc) to 10 (hardest - diamond).
  • 10 - Diamond
  • 9 - Corundum
  • 8 - Topaz
  • 7 - Quartz
  • 6 - Orthoclase
  • 5 - Apatite
  • 4 - Fluorite
  • 3 - Calcite
  • 2 - Gypsum
  • 1- Talc
• Cleavage: A mineral's resistance to being broken and its fracture.
• Crystalline structure/habit: How the crystals grow and look.
• Diaphaneity/Transparency: The ability of light to pass through a mineral.
• Luster: How light is reflected off a mineral's surface.
• Tenacity: How a mineral reacts to stress (e.g., brittle, malleable, ductile, flexible).
  • Brittleness: mineral turns to powder
  • Malleability: mineral flattens under pressure
  • Ductility: mineral can be stretched into wire
  • Flexible but inelastic: mineral bends but returns to original shape
  • Flexible and elastic: mineral bends and stays in the new shape
  • Sectility: Ability of minerals to be sliced by a knife

Specific Mineral Examples

• Diamond: Hardest naturally occurring mineral; made of carbon molecules; excellent insulator.

  • Color: white to blue, pale yellow to colorless
  • Formed at high pressure; Not reactive to strong acids and bases .

• Calcite: Common non-silicate rock-forming mineral.

  • Calcium Carbonate (CaCO3)
  • Brittle
  • Found in sedimentary and hydrothermal environments.
  • Color: generally white to colorless
  • Reacts with weak acids like vinegar and vigorously with diluted hydrochloric acid

• Quartz: Complex silicate (SiO2).

  • Often referred to as a framework silicate.
  • Found in different kinds of rocks.
  • Color: variable, but usually clear, white, milky white, purple, pink, brown
  • Inert and unreactive at room temperature; resistant to chemicals and heat.

• Biotite: Member of the sheet silicates.

  • Color: dark brown to greenish brown to blackish brown.
  • Flexible but breakable.
  • Needs optical, chemical, or X-ray analysis; Not very resistant to weathering.

• Gypsum: Most common sulfate mineral.

  • Water-soluble sediment.
  • Color: clear, colorless, white, gray
  • Limited durability due to hardness; Soluble in hydrochloric acid.

• Talc: Softest mineral; has a soapy or greasy texture.

  • Color: white, colorless, grey, or green
  • Resistant to heat, electricity, and chemicals; Not flammable.

• Olivine: Member of the silicate family; susceptible to weathering.

  • Almost as hard as quartz
  • Color: from translucent to olivine green to glassy.
  • Important mineral in Earth's mantle; crystallizes at high temperatures; Very resistant to chemicals.

• Chlorite: Sheet silicate, similar to biotite.

  • Generally various shades of green; slight greasy texture; produces a phantomed crystal.

• Garnet: Commonly found in different kinds of rocks.

  • Types: Calcium garnets (low hardness, green); Manganese garnets (higher hardness, red)
  • Color varies from red to reddish; Most are translucent.