GeoClassroom Physical Geology Historical Geology Structure Lab Mineralogy Petrology

Composition of the Earth


Earth's crust:
compostion - 95% igneous rock (or it's metamorphic equivalent) - e.g., basalt, granite, granitic gneiss, schist...
8 most abundant elements in crust = (99 weight % and approx. volume) O, Si, Al, Fe, Ca, Na, K, Mg

Most common crustal minerals are:

    - silicates - e.g., quartz SiO2
    - aluminosilicates - e.g., K-feldspar (orthoclase) KAlSi3O8
    - oxides - e.g., hematite Fe2O3

Total earth:
composition - 99% Fe, O, Si, Mg, Ni, S, Ca, Al

    - difference due to core and mantle
      Fe, Mg-silicates = mantle
      S, Ni, Fe = core

- from kimberlite pipes we can tell something about temperature and pressure deep within earth (contain olivine & pyroxene)

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