|Rock is a substance composed of minerals and classified according to mineral composition. Rocks are generally clasified by the processes that formed them, and are thus separated into igneous, sedimentary, and metamorphic rocks. Igneous rocks are formed from molten magma, sedimentary rocks by deposition and compression of particulate matter, and metamorphic rocks by either of the first two categories after being changed by the effects of temperature and pressure. In cases where organic material leaves behind an imprint of itself in rock, the result is known as a fossil.
Mankind has utilized rock since antiquity, and it has played a major
role in human advancement. Ancient monuments and tombstones bear witness
to the symbolism and cultural and religious importance associated with
rock in its various forms through the ages. Rock has also enjoyed
popularity as a landscaping feature – for instance in intricate paving
and walling – valued for its sculptural properties and permanence.
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