Fossil Ammonite, sliced & polished gem quality, Madagascar Cretaceous 100 MY

$55.00 AUD

Fossil Ammonite,

Cleoniceras sp.

Cretaceous Period, 100 million years old

from Madagascar

measures approx. 5cm across

These Ammonites are from the Ambarrimaninga Formation, northwest Madagascar. They are associated with sandstone of the early ‘Albian’ period of the Cretaceous, dating to 100-113 million years ago.
The shell is preserved to the finest detail, and the ‘pearlshell’ affect is the mineralization of the original calcium; often mistakenly called ‘opalised’, it is in fact called ‘Aragonite’ – one of the few organic gemstones. It is produced by living shells and and corals as part of their structure – think ‘pearlshell’ –  but in the fossil condition, converts to a mineral structure that refracts light at different rates, giving a bright ‘opal’ effect.

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Fossil Ammonite, sliced & polished gem quality, Madagascar Cretaceous 100 MY quantity

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