Grain refers to particle or crystal size in rock.
Grain shape.
The cooling rate of the rock.
The name of a rock is usually derived from the sediment grain size.
Granite is considered a coarse grained rock.
Grain size increases in the process of recrystallization.
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clay
It depends on if it is intrusive or extrusive. If it is an intrusive rock, it is formed when magma hardens under the earth and has a larger grain size. If it is an extrusive rock, it is formed when lava hardens on the earth's surface and has a smaller grain size.
Grain refers to particle or crystal size in rock.
1.Grain Size 2.Grain Shape 3.Grain Pattern
Grain size and arrangement.
Grain shape.
The cooling rate of the rock.
the size of a sand grain or smaller
Actually, obsidian doesn't have grains at all. Technically obsidian is a glass, which means it has no internal structure. When geologists refer the the grain size of a rock, they mean how big the crystals that make it up are. Since obsidian has no crystals, it therefore has no grain size.
These characteristics determine a rock's texture.