The Great Mine

The greatest challenge during the search for the lost Peralta Mines has been coming to grips with just how big the mining operations actually were. The cart ruts (on the “Mill Site and Mercury page) told of countless loads of ore going to First Water Canyon, but it didn’t completely “sink in”.

Cerro Negra was pored over, trying to gain more understanding of the orebody and the mining that took place there. Dozens of rocks were gathered, cut, stared at with a loupe, outcrops were photographed, etc.  It was known that the gossan breccias, high in Lithium, and the quartz veinlets were the keys.  Finally it was determined that the Prospect was one very large IOCG deposit with “vents” to the brine lake floor rather then several VMS deposits.

While looking at Cerro Negra with Google earth and rotating the view to look south,  the full magnificence of some of  the mining that had taken place was seen that had taken place, and it was breathtaking.

The “Great Mine” north of the Superstitions was described in the Phoenix Herald and Republican in 1893.  Joe Ribaudo discovered the article in the book “Arizona, the Last Frontier”, by Joseph Miller. Here is an excerpt from the newspaper article:

“Over on the north side of this wonderful mountain so peculiar in shape, standing like the ruins of some great walled city with its tall spires and huge monuments, there has been discovered an ancient mining camp. Whether this mining was done by the Indians and Mexicans of the last century, or whether the operations date to years when de Vaca and Black Stephen started from the coast of Florida to find the gold fields toward the setting sun, may never be known. It is certain, however, that there are shafts and tunnels and drifts and stopes and the clearly-defined walls of a great mine. On the dumps are found tons of rock which without doubt came out of these workings.”

The description is of an underground mine, but how can you see the walls of an underground mine? It was surmised that the only thing it could be referring to is “subsidence” or the “cave zone”. The article said the prospectors found the mine in 1888, and they went on to find ore much richer in the Goldfield area. If this large cave zone was seen it 1888, it certain that it is still able to be seen today, even if erosion has taken place?

The Cerro Negra orebody was formed under a layer of basalt, about 100 feet thick, but there is still abundant jasper and jasperoid that vented through the basalt to the surface.

This is photo below is looking south towards the Cerro Negra ore body. Much of the center of the uppermost portion of of the deposit has been removed that is nearby the rhyolite, forming a deep subsidence zone; It is guessed that a thickness between 20 to 40 feet was mined. It appears that they focused on the richest supergene ore beneath the drainages.

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The caved zone of the Great Mine Looking South

This is what the rhyolite looks like. It resembles the “Imperial porphyry” of Rome.  This rock is key as it is probably the source for the massive hematite breccia found on Cerro Negra, the magnetite  for the alteration of the rock inside the caldera, and the magnetite for the 400-500 foot wide zone of highly magnetic granite that surrounds the caldera.

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Rhyolite Porphyry

There is definite proof of subsidence, and this is on the ridge just north of Cerro Negra (the photo is looking south). This probably appeared long after 1848, after the timber posts and matt rotted and compressed. These are beds of welded tuff that are tipped into the subsidence zone; their edges are not eroded (Flatiron is in the background).

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West side of Cave Zone looking South

Even though a lot of mining took place here, they still barely scratched the surface of the deposit.

One map depicts the mine very well, in typical Spanish style, and actually shows the cave zone. This appeared about 1895 (thanks again, Tom Kollenborn). It is the Hoddenplye Map. (Note the tiny hole through the top of the mountain, again) This map also shows the “placers” in First Water Canyon that were likely the reprocessing of sand from earlier operations that did not use mercury for the gold recovery.

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Hoddenplye Map

The “breccia dike” labeled on the photo above is about 10 feet wide. It looks knobby,  yellowish an blah in the field due to oxidation, but below is a photo of what some of this rock looks like after it is cut; it is jasper and chlorite. There are large cobbles of jasperoid in the dike also.

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The spot labeled “portal” in the “cave zone” photo above had bees flying out from beneath large rocks during the worst of the recent drought. They were going for water. A hole was dug down at the rock face above the bee hole and the brow of a tunnel is believed to have been reached with a shovel; there was a very large stash of saguaro fruit there from pack rats, so there is a significant void.

It is believed that this is the portal indicated on the Ortiz Map below (thanks again Tom Kollenborn). If it is orientated the same as the cave zone diagram above (flipped 180 degrees), it can be seen that they had several tunnels into the caved zone, and they explored extensively along the rhyolite front.  It is believed that some of these tunnels were used to assist in draining water after the exploration and delineation.

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Ortiz Map

Ironically, the first time the author ever stepped foot in the “cave zone” was about 12 years ago.  It was  known that it was something good, but had no knowledge of IOCG  deposits, and it wasn’t even known that the neck of the volcano was only about 200 feet away.

10 contiguous claims were held at the time, and felt it extremely important to put a claim on this ground, so unknowingly put the center of claim marker #11 right in the middle of the cave zone, creating a claim separate from the rest. That one claim, at the same bearing N20W as the other 10, covered almost the entire Cerro Negra deposit and aligned perfectly with the cave zone it is now known.

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Burbridge Map

From almost the time #11 was staked, the author has believed that the satellite workings on the right side of the Burbridge map above (thanks again Tom Kollenborn) were at Cerro Negra, but could not “see” the  relationship and alignment before discovering the cave zone on Google Earth.  It is known now (see the bottom of this article) that the satellite workings are on the contact zone of the Rhyolite.

It has always been the author’s belief that the Burbridge Map with the title, “The Esteemed People of the Salt River District of the North” was a map of an exploration project. The original was dated by the U of A as truly being from the 18th century. Considering the fact Spanish drove a tunnel several miles long to drain the mines of Pachuca in the 18th century, this really was “light work” for them.

Where the crew of Mandozo Segundo Marzo drove their tunnels and sunk shafts in 1753 is where the cave zone is today. They simply blocked out the ore for others to follow, and it took almost 100 years to create the cave zones that remain on and near Cerro Negra today.

The only mining method available in the mid-1800’s and earlier for mining bulk ore was the top-slicing method. This was the precursor to block-caving and top-slicing was used at Inspiration and Morenci, Arizona.

Below is a diagram of the old top-slicing mining method.  The Peralta’s would have used a simplified version of this method, with much less tunneling and no raises (vertical openings). If this is indeed a cave zone shown above, this is how they did it. This takes quite a bit of timber, and the Peralta’s did not have much nearby. This must have been the number one limitation regarding the amount of tons they could mine from underground.

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Below is a photo of the cave zone next to the saddle area. In the background can be seen El Sombrero at the bearing of S65E. It appears like the rock over the stope is STILL subsiding even today on the sides of the cave zone as the decayed timber mat is crushed below.

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A layer of basalt covers the deposit, and jasper, jasperoid, and some gossan has been ejected through the basalt. The ejected material can be found in large quantities today. Because of the abundant limestone cobbles that were beneath the basalt before the IOCG was formed, jasperoid replaced the limestone, and some jasperoid cobbles have been ejected also.

This is what a cut piece of the jasperoid looks like from the breccia dike described above:

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To lead into another aspect of the “Great Mine” subject, below is the Bicknell article that was published in January 13, 1895 in the San Francisco Chronicle.

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The part of the story that is most unbelievable is where they abandoned the shaft that was being mined by the Mexicans, after they threw the bodies inside, and then they saunter on down the hill and find an outcrop of auriferous quartz.   It is not completely clear though from Bicknell’s writing whether they find a second shaft or not, or start from scratch.

It would seem plausible that if they found a quartz outcrop in say 1868?, and it was fairly large, it would still be there today, unless this happened in Goldfield? How could anything like this escape the eyes of so many for so long and be right out in the open?

The possibility of something like this really exists.

Below is a photo again of the cave zone with the location of a vein and breccia pipe added. This vein has a strike length of over 150’, and its width is about 15 feet wide (really). This is interpreted as the auriferous siliceous pipe shown in the Kuroko diagram above. There are dozens of other narrower quartz veins in the cave zone, and veinlet swarms.

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The breccia pipe is made entirely of the material in the photo below. It is laced with drusy quartz, and copper staining can be seen with a loupe.

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These are large quartz crystals covered by chalcedony on the vein that outcrops:

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In conclusion, it is very possible that the stories of old could have happened nearly exactly as they were told.

Sims Ely wrote the first book about lost mines or “lost mine” in the Superstition Mountains, and he coined the phrase “the lost Dutchman” with the title of his book, the “The Lost Dutchman Mine”. In his lifetime of searching for the mine, he did not find much physical evidence, but he found 40 acres of mesquite stumps near LeBarge Canyon (he spelled it that way) in about the year 1900? He found the diameters and the density of the mesquite remarkable in that the Superstitions were very lacking in trees of this quality. He researched the possibilities, and came to the conclusion that the trees were used in the mine he had been looking for.

Sims was not a mining man, and he wondered what kind of mine would use that many mesquite trees. The square-set mining method, which uses a lot of timber, was not invented until well after 1848, and it needs straight, and much larger timber. This miner offers that the twisted trunks of the mesquite, that are not big enough for timber, were only good for the mining method described above, the top slice method. Their intertwined trunks would have worked fairly well to make the timber mat for the technique.

It is not known precisely where the “soldier camp” is that Sims said the stumps were found, but it appears to be about 3 to 4 miles east of the “Great Mine”. It appears that neither the “Great Mine” or the stumps could have existed without the other.

Once the conclusion was drawn that the Prospect was on large IOCG deposit, things began to click. There has to be lots of magnetite for this to be an IOCG. A small, but powerful Neodymium magnet attached to a piece of dental floss was used to conduct a magnetic survey of sorts on the ground.  First, it was learned that all of the soil in Area 1 was loaded with magnetite.  Just by kicking any dirt to loosen it and placing the magnet down brought instant results.  It was clear that the basalt that once covered the breccias was dissolved and leached into the ground.

http://mollymarieprospect.com/IOCG/magnetdirt.JPG
Area 1 Magnetic Soil

By testing the basalt around Cerro Negra it was learned that there was a zone of highly magnetite-enriched basalt near its base.  The next 2 photos show what some of it looks like.  Some of the magnetite-altered basalt is very red inundated with swarms of tiny veinlets of quartz.

http://mollymarieprospect.com/IOCG/spiderwebzone.jpg
Highly Magnetite-Enriched Basalt (glows red under SW UV)
http://mollymarieprospect.com/IOCG/basaltmud.JPG
Highly Magnetic Basalt

The cave zones surrounding Cerro Negra typically have highly magnetic basalt in the bottom of them. Some of the magnetic basalt is inundated by swarms of quartz veinlets.  Below is a photo of the basalt in the cave zone of the “Great Mine” subsidence zone.  The magnet easily stood on its edge.

http://mollymarieprospect.com/magnetic/magvnlts.JPG
Magnetic basalt and veinlets in the Great Mine subsidence zone

The author has always given the Peraltas “superhero” status and has always held the Burbridge map at the top of the list in regards to important maps, tied with the Minas del Oro map.  But because of this, all the attempts to tie the Burbridge map to the Molly Marie caldera were tried over a larger area than it was actually representing.

Finally,  it was thought to place the Burbridge map over an enhanced photo of Cerro Negra as shown below.  There is 100% certainty that this is exactly the place that the Burbridge map is describing.  Note the workings on the edge of the Rhyolite that are below a drainage to explore or mine for skarn deposits and supergene gold.  The perfect combination. Note also the red magnetite-enriched zones that were accessed from underground (very magnetic in the field).  Google Earth does not do well showing vertical relief, but in the field, deep zones of subsidence have shafts near them on the south, west, and north sides.   No wonder the map described in the Salazar Survey (Salazar Survey page) gives the exact directions to the top of Cerro Negra.

The Callejon, or “Straight Pass” also matches perfectly.  The Pass can be seen in the photo below in the caved zone.  The photo does not really do it justice, as it is pretty neat to walk across this saddle in the field.

http://mollymarieprospect.com/IOCG/callejon.JPG
Callejon (The Straight Pass) in the mIddle of the Caved Zone

There are other subsidence zones on the side of Cerro Negra that closely match the shafts shown on the Burbridge map.   Below is a photo of what is believed to be a pillar on the SW side of Cerro Negra that “punched” through to the surface. The pillar is non-magnetic.  The rock surrounding it is highly magnetic and chlorite altered.

http://mollymarieprospect.com/magnetic/pillar.JPG
Pillar that has punched through to the surface

Below is a photo from standing on top of the pillar which shows the subsidence surrounding it. All of the basalt in this subsidence zone is highly magnetic.

http://mollymarieprospect.com/magnetic/SWsubside.JPG
SW subsidence

Below is a subsidence zone on the NW side.  The rock on the right side of the entrance to this zone is extremely magnetic.

http://mollymarieprospect.com/magnetic/NWsubside.JPG
NW Subsidence zone

The Great Mine is complete!

The million dollar question remains: Where is the shaft that Bicknell  described in the article above?  Bicknell interviewed a lot of people and it was unanimous that the mine was accessed by a shaft that was about 80 feet deep.   There is an often-repeated Apache Legend that 40 Apache women and 2 boys left the San Carlos reservation for an entire winter to “hide the mine”.  One story says that they capped it with a cement made of ground-up caliche.  This sounds far-fetched, but the Apaches did know how to make adobe.

Adobe is very erosion resistant as evidenced by the Casa Grande ruins.   There is a fairly large area covered by the material in the photo below in the location labeled “filled in shaft” in the cave zone photo above.  The shaft would have been needed to be capped with material of this nature because of the steep hillside where the shaft is located. There was a small hole dug in this material and the photo below is of the side of it.  There is basalt in the bottom of the hole to right, but it dives steeply to the left.

http://mollymarieprospect.com/magnetic/adobe.JPG
Adobe

Note the fragments of rock that are in this material; is a mixture of a variety of rock of all kinds.

https://mollymarieprospect.com/IOCG/adobe1.JPG
The covered shaft looking uphill

Above is a photo of the adobe area looking uphill.  The small hole dug by the author can be seen.  Recently there must have been the heaviest rainfall out here that has fallen in 15 years.  It caused great erosion everywhere.  By zooming in, it can be seen the veneer of gravel has washed away exposing the adobe.  The adobe area is over 40 feet long uphill-downhill and at least 15 feet wide.  It is surmised it was the portal for an inclined shaft.

This spot also roughly aligns with the shaft that is colored solid black on  the Burbridge map.  Maybe the solid coloring on the original means “filled in”?

https://mollymarieprospect.com/IOCG/adobe3.JPG
The adobe exposed by recent rains
https://mollymarieprospect.com/IOCG/adobegrass.JPG
Camouflaged. The adobe area is by the Ocotillo.

Above is what the hillside looks like today looking down towards the adobe covered area.  The author has questioned the use of adobe because of its color,  but the great amount of rain has allowed for grass to grow this year like the author has  not seen before.  This is how it must have been like 130 years ago, and there must have been a thick layer of brown dead grass to cover the adobe.

The below was posted on the Salazar Survey page, but it is intertwined with the story on this page so it was repeated.

On November 17th, 2019, the author sought to tie up the loose end of properly replicating Photo #1 that Cristobal Peralta had with him, and take it from the bearing S65E.  After some hiking, and climbing up a steep hillside, the correct photo was gained as shown below.

https://mollymarieprospect.com/salazar/new_photo_No.1_anno2.jpg

This turned out well.  This photo was taken over the top of highway 88 which is below.

What was shocking however, is at precisely 180 degrees or at N65W, the following hole in the rock is seen:

https://mollymarieprospect.com/salazar/holetoeast.JPG

This hole in the rock is exactly in the same line with Cerro Negra and El Sombrero.  The chances of this being a coincidence are infinitesimally small.

It is guessed that this was a man-made guide for the many that came up from the Salt River (this is along the shortest route) and they could look through the hole and towards El Sombrero.  Cerro Negra, which holds the Great Mine, could be seen in the same line of sight in this broken terrain, and the direction to get there.

More photos of this to follow.

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