(notes from the CGP revision guides)
- Ores contain enough metal to make extraction worthwhile.
- Rocks are made of minerals. Minerals are just solid elements and compounds.
- Metal ores are rocks that contain varying amounts of minerals from which metals can be extracted.
- In many cases the ore is an oxide of the metal.
- For some metals, large amounts of ore need to be mined just to obtain small percentages of valuable minerals.