STROMATOLITES !

Stromatolites are absolutely amazing because they are the oldest living organisms on Earth and in fact, life on Earth could have started with this reef-building organism. These awesome geological mounds made up of bacteria and algae played an imperative role in early Earths history. They produced oxygen when there was little to none in the atmosphere! Yes this is incredible (!) but it’s not what makes my particular specimen so valuable in price. Take a look at the iridescent luster in the cracks…it is a vibrant purple gemstone that formed after fluids carrying silica passed through the void spaces of the stromatolite. Can you guess what gemstone it is?

You rocked it...it is opal! With opals, generally the more vibrant the display of colors the more sought after the opal. The adored iridescent or opalescent luster that is characteristic of opal is caused by water trapped in the subsurface of the mineral. In some cases the colors will dull as the mineral dehydrates when exposed to air. So basically, I would call this specimen an opalized stromatolite (fossil)! The stromatolite was once a living and breathing thing, now fossilized. It formed slowly over millions of years in a shallow marine environment (normally in a warmer climate), as mats of primitive single-celled cyanobacteria, algae and sedimentary particles built up layer upon successive layer until eventually it hardened creating a laminated sedimentary rock. The precious opal precipitated in the voice spaces at a later stage of course.

Source: Geology Nat (FB)

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