Re: News: Mineral kingdom has co-evolved with life

On Nov 29, 11:37=A0pm, "Robert Karl Stonjek" <rston...@xxxxxxxxxxxxxx>
wrote:
Mineral kingdom has co-evolved with life

(PhysOrg.com) -- Evolution isn't just for living organisms. Scientists at
the Carnegie Institution have found that the mineral kingdom co-evolved w=
ith
life, and that up to two thirds of the more than 4,000 known types of
minerals on Earth can be directly or indirectly linked to biological
activity. The finding, published in American Mineralogist, could aid
scientists in the search for life on other planets.

Robert Hazen and Dominic Papineau of the Carnegie Institution's Geophysic=
al
Laboratory, with six colleagues, reviewed the physical, chemical, and
biological processes that gradually transformed about a dozen different
primordial minerals in ancient interstellar dust grains to the thousands =
of
mineral species on the present-day Earth. (Unlike biological species, eac=
h
mineral species is defined by its characteristic chemical makeup and crys=
tal
structure.)

"It's a different way of looking at minerals from more traditional
approaches," says Hazen. "Mineral evolution is obviously different from
Darwinian evolution-minerals don't mutate, reproduce or compete like livi=
ng
organisms. But we found both the variety and relative abundances of miner=
als
have changed dramatically over more than 4.5 billion years of Earth's
history."

All the chemical elements were present from the start in the Solar System=
s'
primordial dust, but they formed comparatively few minerals. Only after
large bodies such as the Sun and planets congealed did there exist the
extremes of temperature and pressure required to forge a large diversity =
of
mineral species. Many elements were also too dispersed in the original du=
st
clouds to be able to solidify into mineral crystals.

As the Solar System took shape through "gravitational clumping" of small,
undifferentiated bodies-fragments of which are found today in the form of
meteorites-about 60 different minerals made their appearance. Larger,
planet-sized bodies, especially those with volcanic activity and bearing
significant amounts of water, could have given rise to several hundred ne=
w
mineral species. Mars and Venus, which Hazen and coworkers estimate to ha=
ve
at least 500 different mineral species in their surface rocks, appear to
have reached this stage in their mineral evolution.

However, only on Earth-at least in our Solar System-did mineral evolution
progress to the next stages. A key factor was the churning of the planet'=
s
interior by plate tectonics, the process that drives the slow shifting
continents and ocean basins over geological time. Unique to Earth, plate
tectonics created new kinds of physical and chemical environments where
minerals could form, and thereby boosted mineral diversity to more than a
thousand types.

What ultimately had the biggest impact on mineral evolution, however, was
the origin of life, approximately 4 billion years ago. "Of the approximat=
ely
4,300 known mineral species on Earth, perhaps two thirds of them are
biologically mediated," says Hazen. "This is principally a consequence of
our oxygen-rich atmosphere, which is a product of photosynthesis by
microscopic algae." Many important minerals are oxidized weathering
products, including ores of iron, copper and many other metals.

Microorganisms and plants also accelerated the production of diverse clay
minerals. In the oceans, the evolution of organisms with shells and
mineralized skeletons generated thick layered deposits of minerals such a=
s
calcite, which would be rare on a lifeless planet.

"For at least 2.5 billion years, and possibly since the emergence of life=
,
Earth's mineralogy has evolved in parallel with biology," says Hazen. "On=
e
implication of this finding is that remote observations of the mineralogy=
of
other moons and planets may provide crucial evidence for biological
influences beyond Earth."

Citation: Robert M. Hazen, Dominic Papineau, Wouter Bleeker, Robert T.
Downs, John M. Ferry, Timothy J. McCoy, Dimitri Sverjensky and Hexiong Ya=
ng
(2008) Mineral evolution. American Mineralogist.

Provided by Carnegie Institutionhttp://www.physorg.com/news145805221.html

Posted by
Robert Karl Stonjek

This suggests that the Gaia crowd is right on target. I would also add
that it suggest that life is the most stable reaction to the
environment -
one that has not only lasted 4? billion years but has manipulated the
mineral world to fit (as well as the atmosphere, etc.)



.

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