Q for geologists about "supergene enrichment"

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Gregory Crouch

Social climber
Walnut Creek, California
Topic Author's Original Post - Jul 16, 2017 - 10:51am PT
Can any geologists here tell me WHEN the process of supergene enrichment was first described?

More specifically, would silver miners in Nevada and Idaho have understood the process in 1868-1869?

(They definitely knew WHAT happened to their ore as they "sank on the ledge," but would they have known WHY it was happening?)

My google skills, usually solid, don't seem to provide an answer this morning.

The earliest I see it described is in a geology journal dated 1917, but I can think of several easy explanations why it might have been understood long before that.
WyoRockMan

climber
Grizzlyville, WY
Jul 16, 2017 - 12:05pm PT
Great question.

There is certainly a gap between WHAT and WHY. I'm not sure the geochemistry was adequately developed in the 1860's to answer WHY.

There was an 1888 paper describing the solubility of various heavy metal sulfides, more of a WHAT description. [Schurmann, E., 1888. Ueber die Verwandtschaft der Schwermetalle zum Schwefel, Justus Liebig's Ann. Chemie 249:326-350.]

Credit: WyoRockMan

An experimental based paper was published in 1907 which delved deeper into the WHY. [Stokes, N.H., 1907. Experiments on the action of various solutions on pyrite and marcasite, Econ. Geol. 2:14-23]

Happy hunting.
Gregory Crouch

Social climber
Walnut Creek, California
Topic Author's Reply - Jul 16, 2017 - 12:52pm PT
Thank you, WyomingRockMan... that looks pretty convincing that my guys in the late 1860s wouldn't have had much understanding of why it happened.

And perhaps not even much idea of what was happening. I'm not sure at that time that they'd have seen it in enough mines to have noticed that it happened in a lot of them.

Can I have your real name for my thank you statement?

If you don't want to share it here, please email me at gregorycrouch@sbcglobal.net

Thanks, Greg
WyoRockMan

climber
Grizzlyville, WY
Jul 16, 2017 - 07:15pm PT
Greg,

I found this gem, "The Nature of Ore Deposits":
https://archive.org/stream/natureoforedepos00beckuoft/natureoforedepos00beckuoft_djvu.txt

This update was published in 1905 by Walter Reed. It was based primarily on previous work done by Dr. Richard Beck, but somewhat Americanized and with the most recent scientific findings. Nowhere within the text are the terms "Supergene" or "Hypogene". However, the general characteristics and order of zones of enrichment (supergene) are identified.

Reed was an early proponent of aqueous solutions being key to many ore deposits, rather than vapors and gasses. He was also one of the first to classify ore deposits using their genesis as the primary factor. This debate was lively in 1903 as seen here:
https://archive.org/stream/oredepositsdiscu00newyrich/oredepositsdiscu00newyrich_djvu.txt

I'm convinced the term "supergene" was post 1905. The WHY's still had not been sorted out. Pretty sure your 1860's fellows were out of their league scientifically. It is always amazing to me the tenacity and observational skills of the early prospectors/miners in finding ore deposits. Particularly without the knowledge of WHY.

I look forward to reading what you are conjuring up!

Jason Todd


tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Jul 16, 2017 - 09:37pm PT
Interesting question...I suspect the term was 1st used in the 1900s but after 1913.

For example, this 1913 USGS Bulletin "The Enrichment of Sulphide Ores" clearly describes the reactive transport processes that lead to Supergene Enrichment as they were understood at the time but never uses the term "Supergene"

https://pubs.usgs.gov/bul/0529/report.pdf

For a more modern understanding...
http://elementsmagazine.org/archivearticles/e11_5/1_reich.pdf

RE the question whether miners/prosectors of the 1800s understood "Supergene Enrichment", some of the details of Supergene Enrichment and ore extraction are still not fully understood...e.g., role of microorganisms.

The presence of enriched supergene blankets often enhances the economic viability of metal mining operations, especially considering the fact that metal grades of the enriched sulfide zones can be up to 3–4 times higher than the primary sulfide grades (Sillitoe 2005, 2013). However, the often-complex mineralogy of supergene ores poses serious challenges to extractive metallurgy (or mineral processing), and many supergene enrichment
blankets will remain unmined or unprocessed until such time as viable metallurgical processes can be developed. However, harvesting microorganisms from the supergene zone and using them in bioleaching (Zammit et al. 2015) is a promising avenue for a more efficient use of supergene deposits and their enriched blankets.
skcreidc

Social climber
SD, CA
Jul 17, 2017 - 08:29am PT
Would the silver miners in Nevada and Idaho have understood the process in 1868-1869? My guess is a strong no. You bet they were very observant, but they did not have our current and still changing "geochemical" understanding (as T_T pointed out mentioning the role of microorganisms in these processes).

I realize this is late to the party, but I took it on as a challenge to my weak ass computer search skills. Redefining the question as the "earliest geological literature reference to supergene enrichment", I came up with these two references. First was this 1919 reference to "subsequent repeated oxidations and enrichments by supergene solutions of atmospheric origin".

Note the mention of supergene solutions under the chilean local
Note the mention of supergene solutions under the chilean local
Credit: skcreidc

Second was this preface to a second edition (1940) of "Principles of Economic Geology” which first appeared in 1918. It appears based on this that these terms came into common use between the two editions.

Credit: skcreidc
Credit: skcreidc

I think this jives pretty well with the post 1905 assessment, but clearly the terms were starting to be used in a fairly modern understanding prior to 1920. These terms don't sound like anything that would have been used by miners in the mid to late 1800's.
Reilly

Mountain climber
The Other Monrovia- CA
Jul 17, 2017 - 09:20am PT
Poldark woulda! ;-)

The very Poldark mine, a mile from the above.
The very Poldark mine, a mile from the above.
Credit: Reilly
donini

Trad climber
Ouray, Colorado
Jul 17, 2017 - 09:28am PT
Keep this thread on the front page and Kevin Pogue is likely to chime in.
skcreidc

Social climber
SD, CA
Jul 17, 2017 - 09:42am PT
Poldark woulda! ;-)

Sweet jebus Reilly, your wife made you watch that program too? Get into your 50's and your wife starts ditching you for younger men from the British Islands like "Jamie" and "Poldark".


tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Jul 17, 2017 - 10:42am PT


Gregory Crouch

Social climber
Walnut Creek, California
Topic Author's Reply - Jul 17, 2017 - 12:11pm PT
You guys receive the Order of the Heroes of Esoteric Knowledge, Second Class.

Thanks very much.

It sounds to me like I'm on solid ground in thinking that miners in the 1860s and 1870s didn't understand supergene enrichment, either the WHAT or the WHY, and almost certainly not in those terms.

Reading geology from the period is... weird. Hard to make sense of geology without plate tectonics.

Even the concept of a universe of epic, cataclysmic and dynamic change was pretty revolutionary in 1868.

Academic geologists writing about the Comstock Lode did think it was secondary deposits laid down by gasses, vapors, and liquids circulating up from below, but I'd guess that if you asked most miners why the ore was where it was that the answer would have been, "Because God put it there."
Gregory Crouch

Social climber
Walnut Creek, California
Topic Author's Reply - Mar 2, 2018 - 07:41pm PT
Geology people! Could some of you experts please vet this for accuracy?

Please note the included phrase "broad terms." Less technical is better.

although ultimately unsuccessful, their tragedy marked a rising interest in the possibilities of quartz mining. Nineteenth-century miners didn't fully comprehend the complex geological and chemical processes that formed quartz veins, but that didn't change the fact of their existence. Tens of thousands of them striated the mountains and canyons of California and the Great Basin. In broad terms, the veins had formed when hot, high-pressure ground waters carrying dissolved silicon dioxide-quartz, one of the most common mineral compounds-circulated up from deep underground into faults and fissures in the earth's crust. As the water cooled and the pressure relaxed, the silicon dioxide precipitated out of solution, forming crystalline quartz. (Although called quartz "veins," they more closely resembled "sheets" hanging underground, surrounded on both sides by the worthless "country rock"; they presented a visible linear vein only on the surface.) In some instances, other dissolved substances such as sulfur and calcium traveled in the hot water solutions along with the silica dioxide and, sometimes, so did such common metallic elements as copper, iron, and lead. As they fell out of solution, those dissolved materials formed minerals, most of which weren't valuable. But sometimes, on rare occasions, the solutions of hot, circulating groundwaters forced up from below managed to dissolve, transport, and deposit gold and silver and other elements into complex mineral compounds. If the concentrations of precious metals rose high enough, those quartz veins could be valuable, and in the rarest of instances, they could be extremely valuable. Complicating matters, silver ores, even in spectacularly high concentrations, didn't at all resemble the "native" metal they contained.

Thanks!
Dingus Milktoast

Trad climber
Minister of Moderation, Fatcrackistan
Mar 2, 2018 - 08:10pm PT
From my reading the prospectors and miners knew how to look for and (somewhat) follow 'rocks of color.' Faulting drove them crazy. They knew the faults were there obviously, as they were staring them in the face. They did not know the mechanisms that created them though.

Not exactly related to Nevada basin and range enrichment zones under and around buried hot springs, and yet, related:

An epiphany for me was visiting a working CA gold mine into the Melones Fault Zone. Deep inside the earth, they uncovered slickensides that developed on the old subduction zone fault. The guy showing me around did not know exactly how they developed whereas I knew what I was looking at and some of the broad strokes of the plate tectonics that made them. I was thrilled, a half mile under the earth, looking at those smooth slicks of serpentinite, that I undwerstood how they got there.

How could the miners of the 1800s even imagine the kind of faulting that produced them, though? So I got to wondering about the origin of that term, slickenside.

This, from theQuarterly Journal of the Geological Society of London in 1875...

"On the Origins of Slickensides"

Quarterly Journal of the Geological Society of London, Origins of Slic...
Quarterly Journal of the Geological Society of London, Origins of Slickensides
Credit: Dingus Milktoast

http://books.google.com/books?id=QMk__cTwexcC&pg=PA386&lpg=PA386&dq=work+origin+slickenside&source=bl&ots=-sLjFZeMCA&sig=DnMKCtkIiBZkDTWqsQ-_QWNtAdA&hl=en&sa=X&ved=0ahUKEwjk5v_Bos_ZAhUM1mMKHT2pCoUQ6AEIUjAF#v=onepage&q&f=false

Fascinating to be able to chart the development of the ideas.

Thanks for this thread
Cheers
DMT
Gregory Crouch

Social climber
Walnut Creek, California
Topic Author's Reply - Mar 2, 2018 - 09:16pm PT
Dingus, that's a pretty darned neat story.

I've been living with Comstock miners for the last four years, and I must say, I am amazed at what they did. They didn't have plate tectonics, obviously, but they had an immense practical experience gleaned from the face of the ore leads themselves—an experience quite literally impossible for a modern geologist to replicate.

Now that I've got you here, could you please vet the text one or two posts above? I need the mineralization of veins described in the broadest possible terms, but also don't want to be wrong.
Dingus Milktoast

Trad climber
Minister of Moderation, Fatcrackistan
Mar 2, 2018 - 10:19pm PT
Sounds right enough to me but I would defer to the trained geologists who wander around here.

Recently, looking for something else I came across this
http://www.youtube.com/watch?v=StC7mS_FEYI

A pretty cool youtube on gold emplacement including the Nevada geology.

DMT
ontheedgeandscaredtodeath

Social climber
Wilds of New Mexico
Mar 2, 2018 - 10:31pm PT
Hi Greg! The geologists I work with say “ground water” as opposed to “ground waters.” That’s all I got. Hope you are well!
Gregory Crouch

Social climber
Walnut Creek, California
Topic Author's Reply - Mar 3, 2018 - 07:30am PT
Taking geology advice from a lawyer? God help me. ;-)

Got the Christmas card the other day. Give him a sunburn, and your son looks just like you did the day I met you. Scary. (I'm almost finished with "Ranger School for Writers." I'll give you a call when it's over.
Fritz

Social climber
Choss Creek, ID
Mar 3, 2018 - 08:45am PT
Greg: I just sent you an email with my thoughts & a link on quartz veins not being all crystalline & I also agree that it is groundwater (one word) without an s.

MH2

Boulder climber
Andy Cairns
Mar 3, 2018 - 02:16pm PT
Greg: I just sent you an email with my thoughts & a link on quartz veins not being all crystalline & I also agree that it is groundwater (one word) without an s.



Whew! And here I thought some conglomerate features were poorly understood.
BASE104

Social climber
An Oil Field
Mar 3, 2018 - 02:45pm PT
Don't expect an answer from me. I work only sedimentary rocks. Every igneous factoid in my brain has slowly faded since I got out of college during the early Cambrian.
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