International forum: Literature - Rocks and Minerals.
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17 Oct 2015 04:04

What are the three main kinds of rock?
There are igneous, sedimentary, and metamorphic rocks. Igneous rocks are formed from cooled magma. Sometimes it cools on the surface to form rocks such as basalt. Other magma form underground to create rocks called granites.
Many sedimentary rocks are made from worn fragments of other rocks, for example sandstone is formed from sand, Sand consist mainly of quartz a mineral found in granite. And some limestones are made from the shells of sea creatures.
Metamorphic are rocks changed by heat and pressures. For example great heat turns limestone into marble.

About you own ideas how these rocks useful in our present time?

Edited by clixsters / 17 Oct 2015 04:07