Sheridan Creek

I had heard only whispers, and had seen only a very few geodes from this small site, when I purchased a collection that contained several buckets of whole geodes with 'Sheridan Creek' marked on them. When I cracked a few, the blue/gray agate that made up the shell, along with the little Mormon town of Navoo being so close to the area, just clicked together for the 'Blue Navoo' monicker. There were some notes with the collection I purchased about asking permission from a Mr Sheridan, but this area has been split up into several different partials, and I had no idea who now owned the small bluff containing the geodes. Google maps, the plat map, and good luck led me to the right owner and the hunt was on.

The present owner of the property knew he had geodes in the little creek, but he didn't pay them any mind. He is very busy, and quite content, working on his 'hobby' farm (that's what he called it). He said that I was the first person to ask permission to hunt geodes in the nearly thirty years he has owned the property. This owner was very nice and took me down to the creek on his four wheeler to check out the exposure. He hung around and watched me peal off the Warsaw formation shale in search of a hollow geode. He was impressed with how the shale could be worked to reveal the hidden gems, and I cracked a few with a hammer to show him what they contained.

This exposure is a bluff about fifty yards long with potentially dangerous shale hanging above the productive vein. I took great care to make sure the sharp heavy stuff didn't fall on me.

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There was a small pocket in the middle of the vein that had a higher percentage of hollows.

These geodes contained double-terminated quartz with dolomite dominating the secondaries.

The silica for the double terminated quartz is leftover from the acid melt of the calcite nodule during the geodes formation. This leftover silica 'recrystallization' is present in geodes at only a few Keokuk geode locations, though not as common as here.

There was also barite.

The gemmy clear blue barite in this Blue Navoo geode has no kaolinite to cloud its crystal structure, so it is uncommonly clear. Sphalerite showed up only once, and it was in a 'Pandora's box' type geode that broke when the shale was removed from its face.

Notice, in the closeup, the micro chalcopyrite coating the sphalerite crystal. This mineral has crystallized in such a manner that when turned in the sun, all the little crystals are similarly alined, as is the metallic sparkle. This phenomenon was written about in the Keokuk bible, and I was transfixed, turning this geode in my hand. The little blue/gray snowball resting on the zinc crystal is commonly found in the Blue Navoo geodes. When the balls are covered with clear double terminated quartz, the sparkle puts snowballs from other locations to shame.

The secondary common to this location that excites me the most, is aragonite. It is so hard and uncommon to find this mineral in a good crystallized condition. This mineral is unstable and quick to break down into calcite blobs, so crystallized aragonite in the Keokuks, in my opinion, is rare. Not here however. Blue/gray chalcedony with acicular aragonite is common to the Blue Navoo geodes.

In a days work, I cleaned this exposure of all the available geodes and found a half bucket of nice hollow geodes to crack. The ratio of solids to hollows is not good here and I dug over 200 geodes out of the shale, only to keep a few. I will have to wait for the freezing of the winter season to loosen the shale, before more geodes can be found. I made a deal to compensate the landowner, and he will allow me back next spring for another go at the Blue Navoo locality. I will end this story with two geode pics from this location, the first being a snowball geode that has a hollow 'ball' and the last is a yellow quartz geode. Both have the recrystallized quartz that lights up the Blue Navoo with a brilliant sparkle.