Post subject: Fossilized gastropod replaced by precious emerald
Posted: Tue Jun 21, 2016 1:02 pm
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Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Quote:
Fossilized gastropod replaced by precious emerald
Yes, what you are looking at is a natural, though extremely rare phenomenon – quite possibly unique in the world. This fossilised gastropod from the Colombian mine of Gachala has been completely replaced by precious emerald.
Formed from hydrothermal fluids in a shear zone interacting with the rock they passed through, the fossil in the host black shale was transformed. If you look carefully you can also see many small crystals of pyrite, a common inclusion in emeralds from this country. Despite its small size (1.3×1.1×0.9Cm), the preservation is near perfect. This fossil is, as far as I know, unique.
Highly unusual but they've been documented in the past from Columbia. Pretty insane formation but they seem to have been credibly studied. I'll have to dig up the other one I've seen pictures of years back, it was even nicer iirc.
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