Which is the hardest non metallic mineral?
The hardest non metallic mineral is olivine. It is a rock that is found in the Earth's crust and is made up of small, hard, dark-green cubes. Olivine is the hardest mineral on Earth because it has a hardness of 7 on the Mohs scale. What is Nonmetallic? Nonmetallic substances are substances that do not ... Read more...