Earth Science

Natural Resources

Finding and Mining Ores

Study Tip
The 49ers are named after placers—the name refers to the California Gold Rush in 1849.

Ore Deposits

  • Ores are rocks that contain valuable minerals.
  • Placers are minerals found in stream deposits.
  • It’s expensive and damaging to the environment to extract and refine minerals. Therefore, we need to use minerals wisely.
Study Tip
The 49ers are named after placers—the name refers to the California Gold Rush in 1849.
Study Tip
The same way a person may cast a shadow over another person when they stand under the sun, planets or celestial bodies that have aligned themselves cast shadows over one another as well.

Finding and Mining Minerals

  • An ore deposit is a concentrated area of ores, and one that is profitable to mine. Geologists test properties of soil and rocks to locate ore deposits.
  • In surface mining, the earth is blasted open, and rocks are taken to a refinery. This method includes open-pit mining, mountaintop removal, strip mining, placer mining, and dredging.
  • In underground mining, miners dig tunnels deep into the earth to get to the rocks. This method is more expensive and dangerous.
ore containing aluminum
An ore containing aluminum

Ore Extraction

  • After being sent to a refinery, rocks are crushed, so minerals can be separated out of the ore. Some methods include:
  • Heap leaching: the addition of chemicals, such as cyanide or acid, to remove ore.
  • Flotation: the addition of a compound that attaches to the valuable mineral and floats.
  • Smelting: roasting rock, causing it to segregate into layers so the mineral can be extracted.
Ore extration
Ore extraction in a steel mill
Concept Check
  • What are ores? What are placers?
  • What is the difference between surface mining and underground mining?
  • What are some ways to extract minerals from ores?