The Peralta's, and Mercury

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cuzzinjack
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The Peralta's, and Mercury

Postby cuzzinjack » Mon Jun 05, 2017 8:14 pm

Continuing from the second to last thread, Chichilticale, 2 glaring questions remain unanswered:

• The first is, was there pre-Spanish gold mining in the Superstitions area?
• The second question is seemingly unrelated, but will be explained within: Where are the rich placers that are shown on some maps and are present in many stories?

What began the idea that the Peralta’s processed their ore in First Water Canyon was the Minas del Oro map and the thought that it wasn’t the Salt River area as it’s labeled. Subsequently, cart ruts were found leading into the awning area and a dam site surrounded by solid rock was located there also. It was then known that the windmill/awning area was an ore processing site, but no definite proof yet. The Minas del Oro map also shows placers very plainly.

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Evidence of mercury, and a good water source, are the keys to finding an old gold ore processing area. The incredibly rich free-milling Peralta ore, running hundreds of ounces of gold to the ton, had to be crushed to sand and processed with water and mercury in amalgamation patios, or by running the sand over copper-amalgam plates. Otherwise, as much as 50% of the gold would be lost as fine dust, given the crude gravity-only methods that were available at the time (~1700-1848).

A mercury vapor detector was rented, and it was described on this site (Blood in the Water) how the detector was used near the First Water Ranch awning to find incredibly high amounts of mercury in the soil and in the air. It was known then that the awning area, which was built in 1972 to move cattle operations from the original First Water Ranch upstream, was undoubtedly the major Peralta ore processing area, and the mines were located to the west.

At that time, an air survey was done for hundreds of yards upstream from the awning area (to the south), and the detector continued to sound off (there is an audible alarm) with high mercury readings. The upstream readings were dismissed at the time and attention was diverted back the soil samples in an area just south of the awning. Below is a photo of the awning area with items labeled.

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It wasn’t until recently that the connection between the upstream mercury readings, the Minas del Oro placers, and the potential for pre-Spanish mining was made. The outstanding question about the Minas del Oro map is how can there be placers without an orebody? There is not a smidgeon of mining activity or alteration upstream.

An idea was hatched. If the mines were west of First Water canyon, and you were carrying 100 to 200 pounds of ore on your back, what is the best route to get to First Water Canyon and the creek? Assuming the Peralta road to the awning area was not yet constructed, it would have been very taxing and dangerous to carry a very heavy load downhill to the awning area. To check out an alternate route, a hike was made from the trailer parking area to the original First Water Ranch. Imagining there would have been no road there also, it still would have been a very easy grade downhill from the First Water trailhead parking lot. This would have been a much easier hump than packing into the awning area.
Once I arrived at the original First Water Ranch, I had a fresh set of eyes. It was very surprising that 150 feet in front of what would have been the ranch house front door (looking north) are ridges of cobbles in the stream bed reminiscent of placers seen throughout the west, especially the placers operated by Chinese; they washed every stone. Walking upstream from the ranch site, I did not find any of the cobble ridges at all. The creek bed was walked back down to the awning.

This hypothesis was made:

• If there were pre-Spanish miners and the mines were about a mile to the west of First Water Canyon, the site of the original First Water Ranch is where they washed their crushed ore.
• The natives (Apaches? Aztecs?) did not know how to amalgamate and a huge portion of the gold was lost downstream in the form of dust.
• The Peralta’s discovered the lost gold, because they had to process their ore in the same creek.
• The Peralta’s recovered a huge amount of gold here by washing the sand over copper plates soaked with mercury. This would have been very easy money for them.
• This is how there could have been rich placers with no orebody; only the mercury remains to tell the tale.

Here is a map with all the pieces of the puzzle on it:

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By the looks of the stream bed between the original ranch and the awning, it appears that modern-day miners have been working there, say within the last 10-20 or so years. Even though there are deep recesses in the stream bed, there are hardly any rocks or cobbles or even sand in the cracks. It is thought that a powerful vacuum was used to suck up all of the dust off of the rough stream bed when it was dry, or with a high pressure washer, or both. They would have used mercury to finish-up also. Even though it is slightly inside the wilderness area, a “midnight mining” operation in the summer of this fashion would never have been discovered. Below is a photo of the stream bed:

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Given that Spain had a stranglehold on the supply of mercury for the New World for 300 years by controlling the mines in Almaden, Spain and Huancavelica, Peru, where did the Peralta’s get their mercury? It is thought that they definitely would not want to be traced by buying from the government or others, so what could they have done?

It is absolutely incredible to know that there were 3 mercury mines surrounding a volcanic vent near the PERALTA trailhead in 1942. Below is a photo of their location.

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Below is a photo of an outcrop found nearby the vent. Tests have not been run, but it appears to contain some cinnabar, the ore of mercury.

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The mercury betrays the former placers in First Water Canyon, but can gold still be found? The place looks like it has been picked pretty clean, but there should be some places that still hold dust. Back in the day, copper gold pans were used to capture the finest gold after the bottom of the pan was soaked in mercury. This is what one looks like after the mercury has been cooked-off dozens of times.

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cuzzinjack

cuzzinjack
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Re: The Peralta's, and Mercury

Postby cuzzinjack » Tue Jun 13, 2017 8:52 pm

To make absolutely certain that this was an old placer, an experiment was performed. Sample holes in the bedrock swales where the deepest sand and cobbles reside were not attempted; shallow patches of sand were found that were 3 to 6 inches deep and the sand was scraped back until black sand was revealed on the bedrock. The thin layer was removed. This was done at several more spots until maybe a soda can-sized (total) sample, maybe a little more, was taken. It was panned. A 20x loupe revealed globules of mercury and small pieces of amalgam in the concentrate. This is not surprising after the previous mercury vapor survey; most of the gold remaining is amalgam.

It was odd that after using a powerful magnet to remove the black sand, there was still a lot of black sand remaining. Under inspection with the loupe they are rounded, red-brown, oxidized pieces of hematite, some with small patches of amalgam on them. This must be some of the original ore.
It will probably never be known who processed the ore at the original First Water Ranch. It could have been the Spanish before they built the road into the awning area; they had poor recovery, and dug it up and reprocessed the sand decades later.

cuzzinjack

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Re: The Peralta's, and Mercury

Postby cuzzinjack » Wed Jun 28, 2017 9:55 pm

Another sample of the sand from First Water Canyon was gathered (a Ryobi+ vacuum may be good for this) and was processed, but with different procedures.

• Most of the light-colored material was panned off.
• A magnet was used to remove the magnetite from the black sand that remained.

Only manganese minerals should remain. But, after inspecting what was left with a 20x loupe, there was much glassy, golden brown mineral that remained. It has the same density of the black sand remaining and cannot be separated by further panning. After some research, the brown mineral was found to be golden Barite (Barium Sulphate), and the black minerals are Psilomelane (Barium-Manganese oxide) and Pyrolusite(Manganese oxide). The golden Barite and Psilomelane are found in sulphide replacement deposits(like Leadville), many VMS deposits, and in the gold mines of northern Nevada. All three minerals are soluble in brine and can be supergene enriched. Barite is absolutely insoluble in fresh water, and that is why so much must be present. Below is a photo of the Barite and Psilomelane:

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This is more hard evidence that much ore was processed in First Water Canyon at both the awning area and the original First Water Ranch. The processed sand that remains is synonymous to a drill hole into the orebody, revealing the minerology that is below the brine-leached surface of the deposit.

A short hike (~400-500 yards) up First Water Canyon, upstream of the awning reveals that the bare creek bed transitions to ridges of cobbles in the creek bed. The Barite, Psilomelane, amalgam, mercury, and the ridges of cobbles in the creek bed bring a lot of ideas and questions to mind:

• It is the thought that the Mexicans, say between 1840 and 1848 stripped the creek bed to bedrock getting every piece of dust they could.
• By the looks of the cobbles, it appears that people were placering there, as a guesstimate, in the 1990’s, maybe later. How much did they recover?
• Were these people simply hiding behind a false narrative, or were they creating and/or shamelessly propagating a false narrative?

cuzzinjack

cuzzinjack
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Re: The Peralta's, and Mercury

Postby cuzzinjack » Sun Nov 26, 2017 11:36 am

In Canada, over 400 significant VMS deposits have been found, and they have been divided into 5 types and one sub-type. The type of deposit is determined by the type of “donor materials” that were present. The diagram below depicting all of them is compliments of “VOLCANOGENIC MASSIVE SULPHIDE DEPOSITS” by ALAN GALLEY, MARK HANNINGTON AND IAN JONASSON (This paper can be found easily on the web):

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Cerro Negra is a Type #4 VMS deposit (Bimodal Felsic), because of the strata volcano material that was above it and a felsic magma chamber below it when it was formed. Barite, which occurs only with Type #4, and is found at the milling site in First Water Canyon and shown in the photo above, verifies the type of VMS deposit that occurs at Cerro Negra and the other VMS deposits nearby. Below is an enlarged diagram of #4, with the relatively thin layer of basalt added that occurs at Cerro Negra(the perfect trap):

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But the Type #4 deposit in Canada only averages 2.2 g/tonne gold. How did Cerro Negra become so incredibly rich?

Michael F. Sheridan, former ASU geology professor, speculated that ancient placers were dissolved and transported to create the rich gold deposits at Goldfield. Initially, this seems like the only plausible source of the gold, but another more likely source has been found. Almost all of the Canadian VMS deposits were formed beneath deep seawater in a steady-state environment. The Superstition deposits were formed during major rifting and adjacent to a growing brine lake. Because of the gradual inundation by the brine lake, the large quantity of vuggy silica, and numerous low-grade gold assays from rock in the collapse caldera nearby Cerro Negra (.5 g/tonne), it is believed the gold deposits formed in these 3 stages:

STAGE 1: The Dry Stage. Rifting begins and a cluster of strata volcanoes is formed. Because of the lack of an outlet to the sea, massive brine lakes begin to form across southern Arizona, but have not advanced to the volcanoes yet. Above the magma chambers of some volcanoes in the cluster, vuggy silica and low grade, high sulphidation gold deposits are formed (Yanacocha-type). The magma chambers are the gold donor for these deposits.

STAGE 2. The Wet Stage. A deep brine lake (Lake Higley) advances and begins to erode the strato- volcanoes. The brine dissolves the metals in the volcanic debris, penetrates the vuggy silica emplaced near the original surface, and dissolves the gold there. Following the convection cell model, the metal-laden brine is boiled-off near the shallower emplaced portions of the magma chambers. There was likely rhyolite injected into the magma chambers during this stage to add more heat. It is guessed that this massive sulphide ore would carry approximately 2 ounces per ton (Barrick’s Eskay Creek Mine grade).

STAGE 3. The Supergene Stage. After the magma chambers have cooled and the lake receded, meteoric water and residual salt dissolve some of the metals once again (especially below drainages), and they are precipitated at the water table. The final stage results in gold ore assaying hundreds of ounces per ton.

Below is a diagram of what Stages 1 and 2 would look like:

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It is estimated that the Peraltas mined approximately 1 million tons of ore from Cerro Negra between 1700 and 1853. The Peraltas mined the “cream” of the orebody, the barite and supergene zones. Given that the average size of this type of orebody shown above is 5.5 million tonnes, much remains.

Guessing that the top 20 feet of the orebody was mined, just beneath the basalt, only one mining method was available to them: the ancient top-slice method used in the iron mines of England. Subsidence areas at Cerro Negra remain as evidence. There are a LOT of logs needed for this method, and only the larger mesquite trees were suitable for the job. Eventually, the Peralta party had to travel miles to harvest the larger trees. Sims Ely wrote of 40 acres of large mesquite stumps located several miles from Cerro Negra in about the year 1900.

A rule of thumb in the 1800’s is that the cut-off grade (below which is unprofitable) for gold ore was 1 ounce per ton. Because of the high expenses that the Peraltas had (security, women, logging, mercury mining), their cut-off grade was likely double that or more.

A small, modern, high-grade mining operation is in order to continue the mining of Cerro Negra. An underground mine producing only a few hundred tons per day at Cerro Negra could generate the same profit as some of today’s huge operations. And, there is the potential for several more orebodies in the area.

cuzzinjack

cuzzinjack
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Re: The Peralta's, and Mercury

Postby cuzzinjack » Sun Dec 03, 2017 8:07 pm

I dug out a boxed-up mineral collection from the shed to find a good example of golden Barite. The below photo is of a piece of Barite from the Black Cloud Mine in Leadville, Colorado. The orebodies at the Cloud were massive sulphide replacement deposits in dolomite that typically ran 8% Zn, 4% Pb, 0.1 oz./ton Au and 2.0 oz./ton Ag (and a little Cu). But, like the VMS #4 above, the Barite and the gold were the richest at the tops of the orebodies; the gold would typically run an ounce or more per ton. Note that this golden Barite is nearly identical in color to that found in First Water Canyon shown above.

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Cuzzinjack.