Hard Rock Material In Mining
Hard Rock Material is any rock that is resistant and strong, and therefore does not wear away easily. It is usually formed underground, and examples include granite and kimberlite.
Hard rock usually refers to igneous or metamorphic rock. Igneous rock is formed under intense heat from volcanic origins, where rocks crystallized by the cooling of the molten magma. Metamorphic rock is already existing rock (even igneous rock) that has taken form because the changing environmental conditions (for example pressure and temperature) in which it is placed. Igneous rocks are always hard, and metamorphic rocks are generally hard.
Crushing equipment is required to liberate the minerals within the hard rock. Minerals commonly found are uranium, platinum, gold and diamonds.
Fun fact: A simple way to see if your rock is hard is to see if it can scratch glass and steel. Soft rock does not scratch a steel object but can scratch fingernails, and very soft rock does not scratch fingernails.