Just inside the eastern border of California between Yuma and Blythe is one of the best thunderegg exposures in the world. These geode beds have been dug by rockhounds since the 1920s. I took a trip out there in 2011 to find the black agate beds made famous by the Geode Kid. I apologize for not having pictures, but my wife did not accompany me on this trip. The thunderegg exposures are in three 'named' areas. The potato patch is the first exposure encountered and the holes dug here are extensive. A mile further west and the Hauser beds are encountered. The digging here has overtaken the 'road' through these numerous holes in the perlite. Two miles further northwest are the black agate beds. The Geode Kid dug some legendary holes here hunting for the black agate eggs. He also scraped off the overburden on the potato patch exposure several times in the 1960s with a bulldozer before mechanical digging was banned and only hand digging is allowed today. The potato patch is an exposure of mostly geode thundereggs, while the majority of the black agate eggs were a solid nodule. There are other beds named after the type of geodes here, such as the cinnamon beds, the straw beds, etc, but these aforementioned three are the main ones.
Digging at the potato patch is just futile. Where do you start, what hole would you clean out? So many holes, so much overburden, its so frustrating. I dug here for days and found I had a very sore back. The geodes found were OK, but mostly clear quartz and poor matrix surrounding them.
The Hauser beds were the same, lots of overburden to shovel off and very few eggs. The eggs I found here were small and of poorer quality than the potato patch. I dug only a few holes here so my sampling was small. I just didn't see the point after my poor luck at the potato patch. At this point I had 4 days of digging and very few eggs to show for it. This place is really tough and I just needed to chill.
The area to the west of the geode beds is a gunnery range and they were really bombing it up on this day. I climbed up to the top of the hill at the Hauser beds to watch the planes dropping their bombs and to rest my back. On the way up I encountered a small vein of the geode bearing green and brown colored rhyolite. I flew back down that hill to get my pick and bar. After removing the large boulders hiding this exposure, the white perlite flew, literally. The wind was so strong, the shovels full of perlite dust never hit the ground. I am sure my lungs were white also... digging thundereggs is dirty business. I hit a geode immediately and slowed down my pace to get it out without breaking. It was as big as a football and super hollow. Wow, how fast my fortunes had changed. I was so depressed just an hour before, now I had a fresh perlite vein in front of me and I was in geode hunters heaven. This vein was only a few feet wide and was exposed randomly up the mountain. Several holes were dug below where I was digging, and one could see the track of this vein by lining up the holes. I spent two days digging on this vein until I ran totally out of food and water and was forced to make the long drive back to Blythe.
This exposure was different than the potato patch in that the nodules were scarce. Although a few single nodules popped out, it was mostly the green and brown rhyolite rock full of crystal vugs and solid agate. The agate was really pretty and I filled several buckets full of this rough. Several of the nodules were just too hollow and broke into pieces during the extraction. I put these pieces all over the area like Easter-eggs and enjoyed watching the tourist rockhounds filling up their bags. At least they found something sparkly for their long trip out here. This area gets a lot of off-road traffic, and these folks are not geode diggers. They have their hand rakes and emergency shovels and the 'holes' they dig are small. There are no geodes to find here anymore just walking around. You must dig, in the right place, with pick and bar, for hours, to get anything good here. These folks are fun though, and its nice to have the company. They are just out playing and they don't need to find a geode to be happy... unlike me. I headed back into town to stock up on supplies and then back to the Black Hills to find the black agate beds that the Geode Kid spent a year digging.
The road to the geode beds is good enough for my two wheel drive truck, if I take it slow... or fast in the sand. The road to the black beds had a sandy wash I didn't feel comfortable crossing so I decided to camp at the Hauser beds and use the 4 wheeler to get over to the black agate beds. I still wasn't done with that agate seam running up the hill, and it was more sheltered on the south side of the Black Hills, so I could get out of that incessant wind. It was hard to make a sandwich when the bread was blowing away. I found a faint road heading towards the northwest so I unloaded the 4 wheeler and was off to the black agate beds.
Finding the exposure that the Geode Kid dug was easy. A big hill of perlite tailings and the worn paths from the camp to the diggings, told the story of the activity that went on here in the 1960s. There was no way I was going to clean out that hole. The only way to get one of those black agate eggs was to scout around in the area and try to find an exposure that wasn't so dug out. That damn Geode Kid had made it impossible for me to ever find one, I thought. It seemed so improbable to find anything to dig and hopeless depression was setting in... what to do? I decided to hike the whole area, stay off the worn trails, and do some serious prospecting. For the next two days I stuck with this plan, and on the third day it paid off.
I was on a saddle between two hills when I spotted some rhyolite rocks that looked like flattened basketballs. The desert varnish was covering the green and brown color so the signs of agate were hidden. They had a bubbly skin texture though, and I was sure they were some kind of agate. I took out the hammer and banged on one of them. It cracked open to expose a beautiful black agate geode with a gleaming hollow drusy quartz center. The geode had a pretty golden mineral coating a portion of the cavity making a lovely color contrast. The picture does not do this unique geode justice.
I wasn't going to be skunked after all. It sure was nice of that Geode Kid to find these lovely rocks in the first place and then tell me where to find one of my own... I thought. You either love him or you hate him.
The few nodules exposed drew me over to the north hill where I spotted the vein these geodes came from, running up the hill. After much digging I extracted two soccer ball sized round nodules and several smaller ones. This vein was not large and it soon pinched out a few yards up the hill. All geodes that were broken by the pick, were black agate.
Notice in the previous pictures that I am expanding an old dig. Whomever dug this area years ago did not get all the geodes that were there. If you put forth the effort, geodes can be found in the old digs. Just scratching the surface will not be rewarded, you must dig with pick and shovel down through the old tailings to find the nice ones.
I had to see what the big ones contained so I had one of them cut at the Quartzite rock club facilities when I got back in town. The man running the saw said I had to give up the geode to have it cut because I was not a member. Thinking he was surly kidding (It was only fair to give up half and keep half) I said sure. Well... I lost that thunderegg. He was serious and kept both halves. He said they were going to make clocks out of it, so I hope that is the case. I still have another big thunderegg from this exposure, and he will not be the one to cut it. I also plan to dig a little deeper in my new found exposure and see what shows up. This is a picture of the black agate geode fresh off the saw (I did get a pic.)
There are still geodes to be found in the black hills, it just takes some effort to dig down deep enough to find that virgin perilite. My advice is to make a small hole in an old excavation in the middle of the exposure until you hit the vein. When/if you find the vein, the hole can be expanded in the right direction. A good days work with a nice payoff... good luck.
The Geode Hunter