Answer:
diamond, a mineral composed of pure carbon. It is the hardest naturally occurring substance known; it is also the most popular gemstone. Because of their extreme hardness, diamonds have a number of important industrial applications.
Besides the hardness, diamond provides an impressive combination of chemical, physical and mechanical properties:
- Hardness.
- Low coefficient of friction.
- High thermal conductivity.
- High electrical resistivity.
- Low thermal expansion coefficient.
- High strength.
- Broad optical transparency from ultra violet to infra red.
