Question:- What is the hardest rock: igneous, sedimentary, or metamorphic?
Answer: Metamorphic
It is a widely general assumption that the metamorphic kinds of rocks receive the highest hardness among all possible kinds. This development of hardness is due to the conditions under which metamorphic rocks are formed. These are formed when the other rocks which include igneous, sedimentary or even other metamorphic rocks undergo high temperatures and pressures deep in the earth’s crust. These severe conditions lead to the reconstitution of the mineral and these lead to unpacking and interlocking mineral grains. Some examples of hard metamorphic rocks are quartzite originating from sandstone, and marble originating from limestone. Metamorphism is also relative to the generation of new and harder types of minerals. It is worth noting that some igneous rocks such as granite are also very hard but metamorphic rock varieties can be even harder and much more so because of the change that has occurred to them.
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