Composition of rocks
>> Saturday, October 3, 2009
A rock can be defined as a solid substance that occurs naturally because of the effects of three basic geological processes: magma solidification; sedimentation of weathered rock debris; and metamorphism. As a result of these processes, three main types of rock occur:
Igneous rocks- produced by solidification of molten magma from the mantle. Magma that solidifies at the Earth's surface conceives extrusive or volcanis ingenous rocks. When magma cools and solidifies beneath the surface of the Earth intrusive or plutonic ingenous rocks are formed.
Sedimentary rocks- formed by burial, compression, and chemical modification of deposited weathered rock debris or sediments at the Earth's surface.
Metamorphic rocks - created when existing rock is chemically or physically modified by intense heat or pressure.
| Element | Chemical Symbol | Percent Weight in Earth's Crust |
| Oxygen | O | 46.60 |
| Silicon | Si | 27.72 |
| Aluminum | Al | 8.13 |
| Iron | Fe | 5.00 |
| Calcium | Ca | 3.63 |
| Sodium | Na | 2.83 |
| Potassium | K | 2.59 |
| Magnesium | Mg | 2.09 |
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