• What was Piltdown man?
  Some bones, thought to be fossils of an early human ancestor, were ...

• What is an extinct volcano?
  Volcanoes that have not erupted in historic times are said to be ...

• What are ‘hot spots’?
  Some volcanoes lie far from plate edges. They form over 'hot spots' ...

• What are hot springs and geysers?
  Magma heats water in the ground. The hot water often bubbles up in ...

• What are the most valuable minerals?
  Gemstones such as diamonds, rubies, sapphires and emeralds are ...

• Can minerals make you invisible?
  People once believed in many superstitions about minerals. In the ...

• What is the hardest mineral?
  Diamond, a pure but rare form of carbon, is formed under great ...

• What are the most common rocks?
  Sedimentary rocks cover 75% of the Earth's land surface. But igneous ...

• What are birthstones?
  Birthstones are minerals that symbolize the month of a person's ...

• Is coal a rock?
  No. Rocks are inorganic (lifeless) substances. But coal, like oil and ...