Composition of the Earth
The Earth is made up of all the elements listed in the periodic table. The main rock forming elements are:
| O (47%) | Mg (2%) |
| Si (28%) | Ca (3.5%) |
| Al (8%) | Na (3%) |
| Fe (5%) | K (2.5%) |
| Other elements (84) (1%) | |
Combinations of these elements form minerals, which in turn, when combined, form rocks. Rocks are identified by the minerals they contain.
Common minerals and their formula:
| Quartz | SiO2 |
| Pyrite | FeS2 |
| Plagioclase Feldspar | Na/Ca Alumino-Silicate |
| Calcite | CaCO3 |
| Muscovite Mica | Pottasium Alumino-Silicate |
| Augite | Ca/Mg/Fe rich Alumino-Silicate |
| Horneblende | Ca/Mg/Fe rich Alumino Silicate |
| Biotite Mica | Fe/Mg rich Alumino-Silicate |
| Olivine | Fe Mg Silicate |
| Orthoclase Feldspar | Pottasium Alumino-Silicate |
| Garnet | Fe rich Alumino-Silicate |
image of Earth taken from www.ankara.edu.tr/astro/ASTRONOM/EARTH/ESA3.JPG