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Where Does Rock Come From?

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Simon Lazarus Profile
Simon Lazarus answered
Rocks are generally divided into three groups and classified by mineral and chemical composition, by the texture of the constituent particles and by the processes that formed them. These indicators separate rocks into igneous, sedimentary, and metamorphic rocks.

Igneous rocks are formed when molten magma cools and i divided into two main categories: Plutonic rock and volcanic. Plutonic, or intrusive, rocks result when magma cools and crystallizes slowly within the Earth's crust (e.g. Granite), while volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental 'ejecta' (e.g pumice).

Sedimentary rocks are formed by deposition of clastic sediments, organic matter, or chemical precipitates (evaporites), followed by compaction of the particulate matter and cementation during diagenesis. Sedimentary rocks form at or near the Earth's surface. Mud rocks comprise 65 per cent (mudstone, shale and siltstone); sandstones 20 to 25  per cent and carbonate rocks 10 to 15 per cent (limestone and dolostone).

Metamorphic rocks are formed by subjecting any rock type (including previously formed metamorphic rock) to different temperature and pressure conditions than those in which the original rock was formed. These temperatures and pressures are always higher than those at the Earth's surface and must be sufficiently high so as to change the original minerals into other mineral types or else into other forms of the same minerals (e.g. By recrystallisation).

These three classes of rocks are subdivided into many groups. There are, however, no hard and fast boundaries between allied rocks. By an increase or decrease in the proportions of their constituent minerals they pass by every gradation into one another. The distinctive structures of one kind of rock may often be traced gradually merging into those of another. Hence the definitions adopted in establishing rock nomenclature merely correspond to, arguably arbitrary, selected points in a continuously graduated series.
Anonymous Profile
Anonymous answered
Rocks comes from volcano .Rocks are made up of variable mixtures mostly ironic monorails that are bound together in varies ways.
FRANK FAZIO Profile
FRANK FAZIO answered
Rocks are the hard part of the earth. They range in size from grains of sand to continents. Rocks are made up of variable mixtures of mostly organic minerals that are bound together in varies ways. The earth produces rocks in 3 ways. Igneous rocks formed when molten rock is either ejected directly on the earth surface or pushes up near the surface and cools beneath the earth curst this is called magma ejected through the crust is called lava. The 2th type of rock is sedimentary rocks, which is composed of small bits of rocks, mud, sand, gravel, and sometimes plants or animals and become cemented together over a period of time. 3rd metamorphic rocks are formed when igneous or sedimentary rocks are squashed, stretched and cooked and change their appearance and mineral composition.
Anonymous Profile
Anonymous answered
Rocks come from earth lava

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