Spiral Pattern in Australian Opal

September 12, 2023


Photographer: Mila Zinkova    

Summary Author: Mila Zinkova

The Earth Science Picture of the Day for July 21, 2023 "Double Spiral Lichen" reminded me of a pattern in an Australian boulder opal that also displays double spirals. When I purchased the piece of opal shown above, I thought that the double spirals were perhaps fossil snails. They are not. Rather, they’re counter septaria structures. Dr. Adolf Seilacher (a noted German paleontologist) described them as a most perplexing example of diagenetic self-organization. Their patterns are so regular and complex that one might easily mistake them for fossils or for artifacts of an ancient culture. Yet, according to Seilacher, there is no doubt about a purely physical origin. So back to double spirals in the lichen; I wonder if it’s possible that it was simply growing in the moist cracks that originated in the same way the spirals in the opal above did?


Related Links:

Golden Spirals

Video of the Opal with play-of-color