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Post by 1dave on Nov 11, 2020 18:34:20 GMT -7
30 Mya Australia looked like this - It was under a lot of pressure. There were a lot of Earth Quakes - and still are.
There was something spectacular going on in the Great Artesian Basin (GAB).
For that is when Opal happened!
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Post by 1dave on Nov 11, 2020 19:02:53 GMT -7
Lets examine what happened at Yowah - and further on to Koroit - A closer look at the main mining area - Smaller outcrops can be seen exposed further toward the northeast - Examining the mines reveals what happened. Images from: Sandstone above a heavily agitated layer containing the "nuts," and an impermeable layer below. John Elliston explains how silica gel is created in huge amounts during earthquakes!
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Post by 1dave on Nov 11, 2020 20:26:35 GMT -7
The blobs of gel were both shaken and stirred AND coated with limonite that later usually dried out and altered to goethite.
The turbulence is obvious.
Even more so here.
The shells are reminiscent of Moqui Marbles.
What a thrill ro open one!
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Post by 1dave on Nov 12, 2020 7:00:48 GMT -7
Lightning Ridge en.wikipedia.org/wiki/Lightning_Ridge,_New_South_Wales Some of the opal was jumbled just like what happened at Yowah, Where is Lightning Ridge? Just north of Walgett. Lightning Ridge is a LOT WETTER than most opal areas. Looking North
Main Mine Locations
Looking south
An aerial Photo.
Yeabut - what about the opal? Oh yes, some of the best in the world! A black background helps the colors STAND OUT!
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Post by 1dave on Nov 12, 2020 8:27:46 GMT -7
Coober Pedy The name "Coober Pedy" comes from the an Aboriginal term kupa-piti, which means "whitefellas' hole". web.archive.org/web/20120722164421/http://www.cooberpedy.sa.gov.au/site/page.cfmSeen from above Coober pedy is obviously located just offshore in an ancient seabed. A closer look. The green oval is their football field. There are lots of homes and businesses above ground - But the town is famous for those that live below. Coober Pedy produces 90% of the world's opal - But their opalized fossils put them way over the top!
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