Atoms

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(now achieving pressures of the Earth’s core).

From experiments it is clear that most of the rocks exposed at the Earth’s surface today are not stable at these low temperatures/pressures. The minerals that are the most stable at the Earth’s surface are largely clay minerals.

So why are we not adrift in a sea of mud?

Slide 28

Stability and Metastability

Minerals that persist in an environment in which they are not chemically stable are said to be metastable.

Most of the minerals in the rocks at the Earth’s surface are metastable. Given enough energy (or enough time and the right conditions) they will react to form stable minerals.

Earth’s surface

conditions

Slide 29

Credits

Some images in this presentation from:

J Rakovan, Miami Univ., Ohio

Marshak, Earth: Portrait of a Planet (1st ed.)

Plummer, McGeary and Carlson, Physical Geology (8th ed.)

LBNL

chemicalelements.com

NRC

NOVA