Granite is a felsic rock, and comes from the thicker lava flows. It does not “grow” so much as it is formed by volcanic activity. Some rocks, like sandstone, are formed principally by compression, but granite is formed by volcanic action. However, some granites require intrusion into other rocks to acquire other minerals. Thus, the compositions of granites vary depending on the composition of other minerals present.
Granite can be present either by the cooling of lava, which can take as little as a day, or by ascent through the earth’s crust, which can take millions of years.
Granite is not formed by volcanic activity, in the sense of from volcanic eruptions, nor from lava flowing on the surface. Granite forms deep within the earth, not in lava flows; no granite would crystallize in a day – if it did, the crystals would be so small that it would not be granite, but rather rhylolite – which is the identical composition to granite. Granite is a texture term as well as a composition term, and it means large crystals that have cooled slowly, at great depth, over great periods of time – thousands to millions of years.
Also sandstone is not “formed principally ny compression”. Sandstone is just sand grains that are cemented together. Burial, creating a bit of compression, can help but is not the main thing – it’s just a matter of cementing the grains together. That can happen chemically, by dehydration, and various other ways.
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