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Geology of the Happy Jack and Four Aces Mines

April 6, 2016

Let me explain the very interesting geology of both the Four Aces claim and Happy Jack Mine mentioned in my last blog post.  They are both on the southwest side of White Canyon in Southeast Utah. In 1955 Utah Highway 95 was an unimproved track through the desert sand of White Canyon leading north west down to Hite on the Colorado River.  Although it was unsuitable for an ordinary two wheel vehicle, it was shown on road maps as an ordinary highway without any warning.

The floor of White Canyon is the Cedar Mesa white aeolian (wind blown) sandstone of Permian Age, about 270 million years ago. It creates an approximately two mile wide almost horizontal platform with a narrow canyon eroded deep into this floor. The Moenkoepi Formation is widespread throughout the southwest USA. It is a red, brown to purple (particularly in White Canyon) 200 to 350 foot thick very fine grained sandstone which erodes into nearly vertical cliffs rising at the edges of this flat white platform in White Canyon. It was deposited in the early Triassic under a shallow sea some distance from shore ending about 240 million years ago. At that time the sea withdrew and the surface of the formation was dry land but almost level. Meandering streams, and tropical swamps developed with a heavy cover of trees. After a geologically brief time the sea returned and Chinle Shale began to be deposited far off shore reaching a depth of up to 1000 feet in our area.

As the sea began to return at the beginning of Chinle time, the existing shallow, meandering river channels filled in with coarse gravel, small rocks and lots of wood. This forms the discontinuous gray Shinarump Conglomerate Formation. At the top of the Moenkopi cliffs these filled stream beds appear as gray lens shaped outcrops about 50 to 90 feet deep and 100 to 250 feet wide.  The very thick soft Chinle shale above erodes into a not very steep slope gaining depth from its lower edge at the Moenkopi-Shinarump cliff top up to the bottom of the much taller bright red vertical cliffs of aeolean Wingate Sandstone.


Theodore learning to operate a cat in the evening, July, 1955. The cliff is Wingate Sandstone and it is named Copper Point because of the late 19th Century Four Aces copper mine just below it. The soft formation sloping up from the cat’s parking place to the Wingate is Chinle shale. It is the shale of the Painted Desert and the Petrified Forest National Parks. Note the cat-built, switch back road up to the base of the Wingate.



At some point millions of years later when the previously named formations were buried under thousands of feet of over-burden, mineralized water was injected into the area. The very fine grained Moenkopi sandstone and Chinle shale were impervious, but the coarse grained Shinarump conglomerate was a good conduit for this water. There is controversy, but I think this probably happened when the volcanic Henry Mountains were erupted about 23 to 32 million years ago. (The geology of these mountain was intensively studied by John Wesley Powell and Grove Karl Gilbert who named the mountains after Joseph Henry of the Smithsonian and coined the term “laccolithic” to describe their formation. I have original copies of essentially all the early publications by these pioneer western American geologists who were at the forefront of worldwide geology in the late 19th Century.)


The substantial wood debris in the Shinarump adsorbed both copper and uranium, the two main minerals in the water. It is easy to spot the Shinarump as gray lens shaped outcrops cut into the top of the vertical Moenkoepi cliffs under the gradually sloping Chinle shale. Any prospector would find such outcrops interesting. Copper ore is also easy to see because it is brightly colored blue or green. Thus in the 1890s, prospectors identified most of the Shinarump outcrops as rich copper mines. Several were worked for a year or two yielding rich ore.  However, the expense of getting the ore to smelters (via mule train to the Colorado River, one way raft to another mule train down river)  destroyed any hope of profit, so none of the mines lasted long. Most of these mines had become a patented claim and thus remained legal properties forever. The Happy Jack Mine and the Four Aces Mine (about seven miles further along White Canyon) were two of the copper mines which had substantial mine tunnels into the Shinarump. I believe both were worked mainly in 1893. The yellow uranium ore is also easily recognized, but before the 1940s the main use of uranium was to color glass purple, and a tiny amount supplied this small industry.  It was considered an annoying nuisance.



This picture is NOT near White Canyon but it shows the formations which are seen throughout the southwest including White Canyon. The Navajo sandstone at the top of this picture is all eroded away at Copper Point, but the very top of the point is Kayenta sandstone , while the main cliff is Wingate sandstone. The Chinle shale formation is much thicker at White Canyon. Except for being colored purple near Copper Point, the Moenkopi looks just the same.



Fletcher Bronson, his son Grant and Grant’s friend Joe Cooper lived in Blanding. They were the town barber and ran the garage. After World War II they bought the Happy Jack mine claim and re-opened the tunnel, mostly for fun and adventure but with hopes of eventual profit. They mined and trucked a train-car-load of bright colored high-grade copper ore and shipped it to a mill. The mill rejected it because it was so radioactive. After other misadventures, they began to ship high-grade uranium ore and rake in money. By the time I met them in 1955 they were multimillionaires but still worked the mine themselves for fun. (I already mentioned one of them and his generosity and helpfulness in the story about my first day at the Four Aces claim.)

Now the geological origin of the Happy Jack and Four Aces claims were identical and their 19th Century development was exactly parallel with similar very rich copper deposits. So our company geologist, my friend Richard V. Gaines, had every reason to assume that they would contain the same amount of uranium. Unfortunately it turned out that water had somehow gotten into our Four Aces Shinarump formation thousands (possibly millions) of years earlier. Uranium ore is more soluble than copper ore, so the uranium had been leached out leaving the copper largely behind.  Since Exploration Incorporated, for whom I was working, was looking for ten million dollar mines, and after spending a bit over $100,000 a month we had found only a few million dollars worth of uranium, it sold the lease.  Some other company mined out the Four Aces property so there was nothing left of what I remembered when I visited with my children years later.


[[I have corrected some silly mistakes about geology I made in a previous version of this post by trusting 60 year old memories.  I have also changed details about the post-war history of the Happy Jack Mine because I found a newspaper article from 2009.  However, it seems possible that my original memories on this subject were as reliable as those of the author.]]



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