Banded Agates, Sonic Hydrodynamics & the BZ Reaction.

Belousov–Zhabotinsky Oscillation

The generative animatronics of the Belousov–Zhabotinsky reaction is created by non-linear oscillations between two chemicals, usually a bromide and an acid. The arising concentric ring patterns are reminiscent of bacteria and fungus growth, no surprise then that the BZ reaction can be used as a model for biological development.

As with all kinds of patterns of periodicity, the hallmark concentric gradients of BZ reaction seem to crop up in other domains too and at much different growth rates. Periodic variations in the precipitation of specific minerals during Banded Agate formation creates similar concentric arrangements. Where as the BZ reaction takes minutes to produce ornamentation, the formation of Banded Agates can take millions of years.

Flickr provides a great hunting ground for some fine Banded Agates from across the globe. Agateman’s picture of this Coyamito specimen from Mexico radiates a fine colour palette that only Kuler could be jealous of. The Tube Agate shows off the signature ringed pattern in fine pencil line detail, the marble-esque rounded China Rain Eye could be freeze frame from a BZ experiment in itself.

Banded Agate

The Laker Agate has a distinctly bacteriopoetic arrangement of organisms growing upon tangerine facade. Another picture from T shearer, shows fine crisp bands and includes annotation regarding the timescale of agateogenesis – a rough estimate is 10’s of millions of years! Next time you take a break while your computer deals with a 2 hour Sunflow render, take thought.

Hans Jenny
, in his book Cymatics, notes that the effect of sound waves on liquids and powders also has the ability to shape the substances into banded hydrodynamic and precipitative landscapes, once more mimicking the chemical oscillations of the BZ reaction. There is no doubt that further explorations into microscopic crevices and macroscopic craters will yield more traces of this archetypal non linear dynamical system.

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