Item Information

Dimensions (mm) not provided
Weight (carats) not provided
Certified Gemstone


This is  a natural untreated agate from Montana. It is very well polished as it has been tumbled so both sides have a glassy finish.

Weight 59.31 cts app

size 45 x 26 x 5 mm app

Montana  Agate, a name given to the beautiful chalcedony found, most abundantly, in the alluvial gravels of the Yellowstone River, would probably be better named Yellowstone Agate, because its genesis was centered in the Yellowstone Park area. The actual tremendous volcanic activity that produced the conditions necessary for the formation of agate, spanned hundreds of miles and millions of years.


"Eastern Montana was mostly a shallow inland ocean, almost a swamp with huge forests lining its shores and islands of volcanoes spewing forth lava to entomb parts of the forest in lava and ash.  The bowels of Yellowstone bulged and roared and flowed mountains of lava that decimated thousands of acres of mighty redwoods and sequoias for hundreds of miles.  This decimation continued for hundreds of years with layer upon layer of forests growing up and being driven down under the ponderous weight of all the megatons of lava and ash. The hot lava devoured most of the wood in its rush to cover the trees, but some of the shape and ingredients of the limbs remained trapped in the cooling lava.  When the time of the volcanoes and lava was subdued and the rains came, mineral laden silica-water flowed into the cavities and pockets left by the dying trees and bubbling lava.  As flow after flow slowly filled the pockets with liquefied silica, Montana Moss Agate was born."

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Pricing & Details

Bid Increment $1
Starting Bid $20
Auction ID 320528
Watchers 0 watching
Viewed 832 times
Starts 8th Feb 2018 10:05pm PST
Ends 9th Feb 2018 10:05pm PST

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