The mineral olivine
The mineral olivine
Olivine is a green iron-magnesium silicate that occurs very frequently in Earth’s upper mantle and in volcanic melts with a low proportion of silicon. Earth’s entire ocean floor consists of solidified lavas with a high proportion of olivine minerals, as do volcanic regions such as the Eifel, Hawaii or Mount Etna. The example of the typical green olivine minerals on a basalt stone shown here comes from the volcano Mount Erebus in Antarctica. Only at a depth of about 700 kilometres does the pressure in Earth's mantle become so high that olivine changes into perovskite-group minerals, in which the same atoms are ‘pressed’ into a denser crystal lattice. The latest research results derived from quake waves now show that the mantle of Mars, which is just over 1500 kilometres thick, is more like the upper, olivine-rich mantle of Earth than the lower mantle.
