Play of Color
: Imagine a gem so iridescently beautiful that a phrase, play of color
, is coined just to describe it. How does an ordinary sludge of sand and water, boringly described as hydrated silicon dioxide (SiO2. nH2O), express every color in the spectrum of light?Precious opal
is formed when a solution of silica seeps through cracks in a rock very slowly
: at a rate of one centimetre thickness every five million years. Under pressure, spheres of silica 150-300 nanometers wide, deposit in crystalline arrays. This regular packing, spaced close enough to the wavelength of light, has the effect of a diffraction grating, and the scattered light can be described by Bragg's Law. Nearly all the earth's supply of precious opal comes from Australia, formed in the Cretaceous period, more than a hundred million years ago. Eric the Pliosaur
: Now imagine a massive thick necked beast that once cruised through the Late Jurassic oceans, with a jaw four times stronger than T. rex
and 10 times more powerful than any living creature. 150 million years later, our pliosaur has been "opalized" to an iridescent sheen, his fragments discovered by a lucky miner in Australia's Coober Pedy and sold for $250,000 USD to a wealthy businessman who subsequently lost his fortune. Christened Eric the Pliosaur by a mischievous archaeologist who was asked to put the bones together, after Monty Python's Eric the Half a Bee, the fossil turned out to have a fish inside its belly, fittingly named Wanda. After a public campaign, Eric was eventually purchased for display by the Australian Museum. What a thrilling journey for Eric.
► Musical accompaniment: Monty Python - Eric the Half-a-Bee (1972) Half a bee, philosophically, must ipso facto half not be
.But half the bee has got to be, vis-à-vis its entity - d'you see?But can a bee be said to be or not to be an entire beewhen half the bee is not a bee, due to some ancient injury?
► Pliosaurus: http://en.wikipedia.org/wiki/Pliosaurus
► Opalized Fossils: http://www.australianopalcentre.com/fossils.php #ScienceSunday #fossilfriday