East San Raphael Swell Stromatolites

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The San Rafael Swell became prominent 138 Million Years ago.

I think this was 138 Ma.





ugspub.nr.utah.gov/publications/geologicmaps/30x60quadrangles/m-267.pdf

Jm = JURASSIC Navajo SS, Jct = Curtis, Js= Summerville, Jmt = Morrison Tidwell, Jms = Salt Wash, Jmb = Brushy Basin



To get to the Stromatolite Agate, turn off U.S. 50 onto Utah 24 headed south.

BTW, If you are wondering where the name "Shadscale Mesa" came from . .



It was named for the most prominent plant found on the mesa.



The east side of the San Raphael Swell is an amazing location to visit and collect.
Turn south off US 50 on Utah State Road 24 toward Hanksville.



Just looking around is worth the trip.
I place a Gypsy Curse on anyone who tries to remove truck loads of material from here!





This area was once a lake filled with stromatolites that have been replaced with red, yellow, and purple jasper. It is often found with hollows that have filled with dog-tooth calcite or celestite crystals inside. Stromatolite surface buds form what is locally known as "Grape Agate."





Here are five views of one of my finds.

Jan 13, 2014 12:10:43 GMT -7 @herchenx said:

1dave I posted a thread in this trips and shows section, but this looks to be within a day's drive, have you seen any celestite or purple agate out of here? What sort of land is this? BLM, state land or something else?

Thanks for any help, looking for a fun place to take the kids this coming weekend and wondering if this might be an option.

Mostly BLM, a few state squares, lots of sand. Don't get stuck.
Yes, some of the agate is purple, most is red, some yellow. Hollows contain calcite crystals, some celestite. Bring a shovel as the best full nodules have probably been picked up unless there has been a recent storm.

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Jan 13, 2014 16:43:52 GMT -7 @jamesp said:

Please explain the third photo. Is that a limestone shelf with(red) stromatolites laying on top of it and is the top of the limestone shelf the top of the lake bottom?

Do those stromatolites grow on the bottom of the water body? Do they grow in shallow water like the right side shelf? Is the left side where the lake was deeper or is that a wash?

Curious. My coral heads sit on a limestone shelf rolling out like bowling balls as the river washes the bank soil sitting on limestone bed. Looks like the same scenario.

There is a LOT of silica in that limestone! They formed in shallow lakes, were buried, then new growths started on top. There seems to be many layers.
This modern photo shows how they grow - and break up! I think most of what I found were broken before they were buried and had been rejected by previous searchers.
The warty surface on the middle stromatolite shows where the "grape agate" came from.

[Admin]

Feb 22, 2019 15:04:51 GMT -7 @miket said:

A friend of mine gave me these and I'm not quite sure what to do with them so I thought I'd see if anyone here had worked with them.
Cut and cab or tumble?
I don't want to waste them, they're really cool.

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Feb 23, 2019 9:12:06 GMT -7 @rockjunquie said:

A little different, but I had some from Indonesia. Very cool stuff.