Monday, February 23, 2009

Unlike Diamonds, Most Minerals Not Forever

From Live Science:

Diamonds may be forever, but that's not true of most minerals. In fact, about two-thirds of the 4,300 known minerals on Earth today owe their existence to biological processes, and thus evolved fairly recently in geological terms. So says Robert M. Hazen of the Carnegie Institution in Washington, D.C., who with seven colleagues identified three phases of mineral evolution.

The first phase began more than 4.55 billion years ago, as the solar system started developing. Chemical elements came together, forming about 250 simple minerals that in turn coalesced into planets. On Earth, the second phase stretched from 4.55 billion to 2.5 billion years ago, starting with the violent collision that formed the Moon. Earth's temperature and pressure varied wildly; plate tectonics began churning the planet's surface; and volatiles appeared, such as water and carbon dioxide, helping to redistribute the elements. Those changes enabled the evolution of some 1,250 new minerals.

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