Shamalama Summer Vacation Day 3

[Shamalama]

Day three - Tuesday, September 1st

Today I headed out from Evanston, WY towards Provo, UT. More specifically I was headed to the mountains along the west side of Utah Lake near Pelican Point. I had read that there were some minerals and fossils to be found in the hills. My first stop was at a cut at the top of a hill through some limestone that purported to have some Onyx and Optical Calcite. I followed the directions and found what I thought was the turn off to the quarry. I drove along the gravel road for about a tenth of a mile and then it quit at the base of the hill. Figuring that this was where I had to start hiking I proceeded up the hill. By the time I got to the top I saw another road that came up to near the top of the hill. I could have saved myself some hiking! I got to the cut, it was only about ten feet wide and fifty feet long with lots of rubble to look through. As I’m looking around I notice that there are dozens of spiders and their webs all over the place. I guess this is a good place to catch a meal. After looking around for about half an hour I didn’t find any of the Optical Calcite and only a couple of pieces of decent Onyx. I scampered down the mountain to my vehicle.

View of the hills in the morning light

The next stop was to a fairly famous site in mineralogical circles. It’s another small cut at the top of another hill but this time I found the right road to the top. What I was looking for here were Limonite Pseudomorphs after Pyrite. These are quite common in parts of Lancaster county back in PA but the ones found at this site are generally sharper and larger. What I found is a very shallow cut into the top of the hill that exposes some white and red soil with a few Limestone ledges here and there. I was excited to start looking and saw all kinds of interesting things on the ground at first. Much to my dismay many of the objects that I think are black Limonite crystals turn out to be the pieces of clay pigeons, shotgun shells, rifle shells and miscellaneous debris that had been used for target practice at some point. I find a pit that had been dug into the side of the hill and check it out. I get lucky and find a few small Limonite crystals and am trying to figure out how and where they are distributed. I seems they have weathered out of the Limestone at some point and become part of the talus soil.

The pit

Crystal poking out of the wall and crystal once extracted

I’m able to pick a few more out and even find a couple of chunks of Limestone with Limonite crystals still in matrix. As I head back to my car, I look at another, shallow depression that someone dug into another part of the hillside and find a perfect cluster of large Limonite crystals just waiting for me to pick them up! That made my day and I then spent a few more minutes looking around but did not find anything as good as that one again.

The larger crystal in the ground and once extracted

Crystals still embedded in the host limestone

Finished with this site I head out to the location I have been looking forward to for a few weeks, a quarry into the Manning Canyon Shale. Ebrocklds gave me the location and described what colors of shale to look in for different plants and animals. It took me a little driving around the quarry pit to figure out that there was no easy way into it as all ramps were blocked.

I finally settled on a location to foray in from and started looking at every piece of shale that I came across. I wasn’t having much luck but then I came across a few small, single leaves and lepidophylliites (?) impressions. Then I found a partial frond from what looks like a Pectopteris or maybe Neuropteris. I’m not familiar enough with the flora from this formation and need to look through the .pdf files that ebrocklds posted a while ago. I'm using the common names of plants that I recognize from the Pennsylvanian period but these plants are from the Mississippian (which fills in another hole in my collection!)

Fern frond

Possible seed?

I skeedadled out of the quarry after only a hour of looking because I heard someone practice (I hope) shooting very close by and I didn’t want to end up a target. A side note here, at every site in these hills and as evidenced in every road sign that I saw in the area, shooting things seems to be quite the popular activity for the locals. I don’t have any problem with that, I just wish they’d stay in one designated area like a shooting range and not leave such a mess in other areas. Enough of my soapbox, onto the next site: Dugway!

[Shamalama]

The geodes from Dugway have been a fascination of mine since I was a little kid. They have light brown to reddish striated Rhyolite surrounding hollow spaces filled with druzy to crystalline Quartz. They also fluoresce brilliantly under short wave UV due to the presence of uranium salts in the Quartz. The uranium is such a miniscule presence that it wouldn’t even set off a Geiger counter so no worries there. I made a cross state run from Pelican Point across some beautiful high desert country. As I’m approaching the turnoff to the Geode dig site I spy a small quarry up on a hill. At this point I’m in the Thomas Range which is basically a huge Rhyolite mountain that is heavily eroded. A quick geology lesson: Rhyolite is the extrusive equivalent to Granite. That means that while Granite is formed by cooling underground, Rhyolite is formed by viscous magma flows on the surface. The rate of its cooling will determine what kind of rock forms. If it has lots of time to cool then it will form an Obsidian like rock. Faster cooling will result in frothy or foamy texture or just have lots of large gas pockets where geodes later form. All of that was just to tell you that I went up to the quarry (after a fairly stressful drive up steep inclines covered in large rocks) and found some small crystals of Topaz, Garnet and possibly Hematite, Bixbyite and Pseduobrookite. The Thomas Range is well known for its Topaz and on the other side of the mountain from where I was is an area called Topaz Mountain. Here one can find Topaz crystals in the rock or weathered out and lying in the dirt. Most are not large enough for faceting into gems but some have been found that can be. Mostly the pieces I picked up will be for my collection and to say that I collected at the Thomas Range.

The Rhyolite quarry from a distance

The Rhyolite quarry cut itself

View from the quarry of where I had to park

Topaz Crystal

Pseudobrookite

Garnet or Bixbyite

Now, finally onto Dugway! I got back on the road to the geode site and made the turn off onto a poorly graded road. After a few false turns I made it to the correct road towards the site (keep in mind this is all back country gravel/dirt roads that are meandering every which way… and not many signs!) and, as I was climbing a steep hill, came upon two vehicles with fellow rockhounds. They asked if I’d seen their third vehicle that they left behind a ways back and I told them yes and that it was still in one piece. They confirmed for me that I was on the right road to Dugway and only had about a mile or so to go, as well as describing where they had just dug. I finally get to the site and I find not one, but three large pits dug into the earth. Each pit was about 20’ long and deep and ranged from 15’-30’ wide.

A view of the pits and the dump piles

A view into one pit

I’d never collected at this site and had only a vague notion of what to do. If I hadn’t been dilly-dallying up at the Rhyolite quarry then I might have made it here before the people I met along the way had left and could have gotten some pointers. I looked around a bit and there were hundreds of broken geodes littering the ground and pits. There were small, golf ball sized up to basketball sized broken halves all over the place. Heck, I didn’t even have to dig if I just wanted to pick from the leftovers. I choose a few that looked interesting through the light coating of white clay that covers everything figuring I could wash them off later. I was determined to at least see if I could find some whole geodes in situ so I got out my pickax and took a whack at a promising area.

My attempts at digging into the clay layer to look for geodes

After a few minutes of digging I see why so many geodes can be found broken open; since they are buried in hard clay (the result of the weathering of the surrounding Rhyolite) and the only way to remove them is to dig, it’s not uncommon to break them as you attempt to locate them. After about twenty minutes of digging I wasn’t finding much intact so I decided to explore a little more. I found many other shallow pits nearby and recalled that these deeper pits are dug with a track-hoe by the Crapos (yes THE Crapos who also run the U-dig trilobite quarries) to benefit themselves, as I think they have a claim, as well as other rockhounds. So all these other smaller pits are much older or just people trying to find other areas to dig. I went down into another of the larger pits and saw where a previous group had been digging along the wall and saw how the geodes look “in situ”. Many are chains of smaller geodes that link together so that as your trying to remove one you break another. I finally put two and two together and realized that this pit I was in now had been dug within the last few months and that maybe, instead of breaking my back trying to dig for them, I should look at the tailings piles left from the excavation. It doesn’t take long for me to find half a dozen palm sized geodes that are intact and “feel” hollow. I break a couple open thinking they are solid and one turns out to have some beautiful, sharp Quartz Crystals lining the interior. The other has an unattractive druze so I toss it back. The rest I will save and have cut someday hoping that they will be winners!

Geodes from the earth

Cleaned up

I finished my day by heading towards Delta (and my hotel) but not before stopping off at a couple of sites that wound up being unproductive along the way. So today didn’t have many fossils but there was plenty of stuff found!

[Auspex]

Whew, what a day; I need a beer!

Hate to admit it, but min'rals are cool

[lordpiney]

those are some beautiful geodes dave!

[Shamalama]

Thanks, guys! I embrace the minerals as well as fossils and now will have to dedicate an entire day to Dugway/Thomas Range the next time I am out there.

[Terry Dactyll]

Shamalama.... Good stuff, excellent finds.... Very nice to see the locality photos....

[mommabetts]

Good report, made me feel like I was right there with you. Thanks for sharing.