[Rockhounds] Science News article about banded iron formations

[Alan Silverstein]

The June 20 issue of Science News contained an interesting feature
article about new research into banded iron formations.  And apparently
it's publically available here:

  http://www.sciencenews.org/view/feature/id/44350/title/The_iron_record_of_Earth.s_oxygen

It ties together reduction of nickel in the oceans => less methane in
the air => "great oxidation event" => precipitation of iron and silica.

I found it interesting partly because I've collected "ironwood", which
is orange/red/purple, magnetic/hematite plus agate, in eastern Wyoming.

Cheers,
Alan Silverstein