Geologic
Time: Proterozoic (2.2 to 2.4 Billion Years Old)
Size:
117 mm by 70 mm, 8 mm thick.
Fossil Site:
Hough Lake (?), Port Handford, Western Australia
Description:
A polished slab of what is termed locally “Tiger Iron”.
Known as Jaspelite, it is a banded structure of Tiger Eye, Red Jasper,
and Hematite. Stromatolites are remnants of the most ancient of colonial
organisms. Stromatolites are fossils that are the result of the work
of simple blue-green “algae” or Cyanophytes, which lived
in chains or mats covered in a jellylike substance. By taking in carbon
dioxide as a food source, the precipitate limy deposits on the jelly
that builds up in layers. Thus these organisms build up stony supports
for their colonies. These mound like structures can be anywhere from
several centimeters to several meters in height. The production of
oxygen is thought to have led to the “rusting of the seas” which
brought about deposition of extensive iron deposits such as the
Mesabi Range. Hematite is an iron mineral, and is one of the components
of this banded structure (dark bands). Stromatolites have persisted
to the modern day in such places as Shark Bay, Australia where
they
continue their billions of years old lifestyle. This one is quite
natural in appearance on all but the surface which has been given
a high polish to show off the myriad of colors.
Also
see: Stromatolites
Across Geologic Time |
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