Soil samples for placer indication

[chickenminer]

Just wondering if any of you guys have used soil sampling to find and then prove out a good placer prospect?

So I guess the answer to your original question is no. While it seems like a good first indicator I sure would want to find a more proven definitive method of testing a placer deposit before investing.

Interesting question though, for placer ground. For what it's worth I have had a company that was prospecting in the area for hardrock deposits ask permission to do soils on my claims. While some of the samples came back an anomaly none threw up any big red flags.

[Geowizard]

To Slatco's question;

I have never used or done soil sampling to find or locate a placer GOLD deposit and yes, It is an interesting question!

Why not?

The answer to "Why not?" is related to several factors that affect the relevance of soil sampling in general and the probability of discovery of a "placer" GOLD deposit as a result of it...

There are no examples in any of the literature that I have read of anyone using soil samples to locate a potential placer GOLD deposit with one exception. That was a Geologist and former member of this Forum that was looking for a placer deposit near Fairbanks around Old Murphy Dome on Hattie Creek. It was a long story that ended in no viable discovery of a placer deposit and he walked away. That prospector moved to proven ground on a tributary of the Middle Fork of the Chena River.

There are methods and techniques of prospecting that are known to work. We know they work from what we read that includes the "written history of prospectors and prospecting". I cannot recall any discussion of soil sampling for the purpose of chasing a placer GOLD deposit.

There ARE examples where soil samples have been used to find LODE deposits. It is also reasonable to expect GOLD will be found between a LODE deposit along an erosion model that terminates in a drainage. Prospectors understand that's the nature of erosion and the known behavior of heavy minerals and metals. Conventional wisdom dictates otherwise because of scattering and dilution.

Traditional placer prospecting has been to find a placer deposit from prospecting along streams and rivers. All of the discoveries of placer deposits that I know of and there are too many to cite have been discovered through a process of panning at the waters edge.

Why?

The reason is because LODE GOLD is in practically all cases low grade gold. The particles become widely scattered during the process of erosion. Widely scattered, low grade GOLD offers little hope for discovery. The laws of probability dictate the chances of discovery become one in a million at the gram level. The greater probability is that a prospector will discover GOLD at the "source" or at the final resting place in the form of a relatively concentrated deposit.

Ryan Gold;

The evidence is clear and there is an important lesson to be learned. Shawn Ryan improved the probability of discovery by increasing the "odds" through a process of collecting tens of thousands of samples!

Reversing the course;

Collecting soil samples to discover a placer GOLD deposit has "probably" been attempted by prospectors from time to time and place to place over the past several hundred years. Evidently, the laws of probability were never in their favor and the process never gained much recognition.

If anyone can cite a publication on the subject, please do so!

- Geowizard

[PickaxeCA]

@Geowizard - it depend what is defined as 'soil' within a soil sampling program. Perhaps the idea or concept behind soil sampling could be applied to placer, but without 'soil' as the medium of choice.

For those who may not know, soil sampling is a geochemical exploration technique that involves creating a survey grid of lines with defined spacing in between samples, and in between lines.

The purpose is to identify a large ore body or mineralized system, and by sampling perpendicular across known trends e.g. if mineralization trends NE, you sample from SE to NW to go across it.

Placer seems like more of a 3D model to me. Paystreaks, lines and layers are the currency of a placer deposit, not some deep ore body 300 feet below surface that you need a diamond drill to poke at.

Using a systematic grid approach to placer sampling where you sample every 15 feet on lines that are 15 feet apart as an arbitrary measured interval certainly could not hurt, especially if you can quickly dig up your sample and classify it dry e.g. to 1/4" to get meaningful information e.g. speck count by mesh size, gold character (rough, angular and low travel versus rounded and well travelled), black sand percentage, does the pan feel 'heavy', etc.

Perhaps the takeaway here is that casual test panning is very different from a planned survey.

In the latter (a planner survey), the objective is good data to enable decision making.

In the former (casual test panning), the objective is good speck count, with few or no notes taken.

I suspect that most people just test pan wherever it 'looks good' rather than executing a methodical sampling program with a defined number of samples, measured distances in between samples, etc.

Perhaps the takeaway here is to be way more rigorous when sampling for placer in terms of survey grid design, note taking, data capture e.g. GPS coordinate, sample depth, material description, photos, videos, notes, speck count, gold character, black sand percentage, etc.

This stuff is table stakes for soil sampling in mineral exploration, but how many hobbyist prospectors are that rigorous in their with sampling methodology?

One could easily take dozens of small classified samples, put in labelled ziplock bags. Pan all at the creek, and note the data for each sample.

Then, use some type of colored flags or flagging to indicate the best sample sites in the field (remove when done for the day).

At home, use your favourite GIS software (e.g. ArcGIS, QGIS, etc) or even Google Earth to plot the sample sites on a map using UTM, Lat/Long, KMZ, etc. Bonus points if you can use data viz techniques to have changing dot size and colour for your better gold samples (this is what I do for hard rock gold, arsenic, antimony, etc).

The result would be a soil-sample-like map, but for placer. I could see that being useful for reconnaisance scale placer prospecting in unmined benches way above present water courses, that possibly haven't been touched due to a complete lack of water.

[Geowizard]

The age of Discovery;

It's easy for GOLD prospectors to become "myopic". It's a case where we develop a view of the world around us based on a narrow view formed from our limited "experience".

For example, in my early years, when GOLD prospecting and spending hours digging and scraping dirt, searching for minerals in any form, I would find an exciting specimen in the form of a thumb sized piece of chrysocola. It pops right out! I went through the trouble of taking it to the Arizona Department of Mines and Mineral Resources. In return, I would get humiliated with comments like; "Well, you're a long ways from a copper mine!"

Learning from our predecessors;

Early Spanish explorers (Conquistadores) AFTER having sailed across the Atlantic Ocean went to work prospecting North America looking for the lost city of "El Dorado".

https://en.wikipedia.org/wiki/El_Dorado

https://en.wikipedia.org/wiki/Conquistador

They shipped TONS of GOLD and Silver back to Spain!

The Conquistadores used the best tools available, their eyeballs, in their search for what today, we call "iron gossans". We know now as they probably knew then, an iron gossan results from the "halo" created by Iron sulfides becoming oxidized forming an orange - red, sometimes yellow when arsenic is present, very visible coloration of the surface.

Minerals like copper have a range of blue and green coloration. A little copper goes a long way when it becomes an oxide! Gold is often associated with iron minerals and copper. Iron and copper are good visual markers. Arsenic related to arsenopyrite is a very important visual marker. These minerals express themselves because their concentration is anomalous to the degree that we can "see" them.

Minerals in soil;

What is Soil?

Natural Resources Conservation Service
U.S. DEPARTMENT OF AGRICULTURE

https://www.nrcs.usda.gov/resources/edu ... ansfers%2C

A good reference, Nature.com provides a better definition with illustrations:

https://www.nature.com/scitable/knowled ... -67647639/

We can summarize from the information we read that soils are mostly organic and yes, there are minerals in the soil.

Soil Geochemistry;

Much study in recent decades has been directed toward various means and methods using sensitive analytical tools. The tools range from AA and ICP spectrometers for inorganic analysis of soils and plants to optical methods using laser technology and x-ray fluorescence spectrometers. The measurements are in parts per million and for GOLD, measurements in parts per billion.

Oxides of all of the metals are plentiful except those metals that do NOT form oxides like GOLD!

Tools, APPs, GOLD and the Cloud;

The Geochem App can be found here...

https://www.sciaps.com/industries/geoch ... JcQAvD_BwE

A whole new world of analysis?

The Geochem Pro App?

Ready to Order?

Where's the Gold?

START an Order and hit the SUBMIT button!

Don't confuse minerals like Lithium with GOLD.

https://en.wikipedia.org/wiki/Lithium_oxide

We are flooded with technology and claims of all sorts having little or no basis in material fact. Lots of "Buzz" words!

Wheat or Chaff?

What it boils down to for the common GOLD prospector is being able to separate the wheat from the chaff. We aren't going to mine micron GOLD or nano GOLD. We aren't going to mine Chaff sized particles of GOLD. Rational prospectors don't get excited about fine gold. The reason is obvious. Fine GOLD takes the effort involved in clean-up to another level - beyond which, the laws of diminishing returns prevail.

A successful Placer miner wants to mine "wheat" sized GOLD or larger. Prospectors have an objective. The objective is to find GOLD in sufficient quantity to warrant a prudent man to expend his money! To that end, if we look around at our fellow GOLD prospectors, we can ask, what are they doing right and what are they doing wrong?

You be the judge!

- Geowizard

[Joe S (AK)]

"For what it's worth I have had a company that was prospecting in the area for hardrock deposits ask permission to do soils on my claims. While some of the samples came back an anomaly none threw up any big red flags."

Dick,
I have seen the same sort of thing happen at a friend's claim a few years back.

While visiting my buddy Dan on his claims a never-before-thing had happened. A helicopter had landed at the airstrip (!) and a few minutes later a youngish fellow came striding up to introduce himself to Dan and I.

This fellow owned an exploration-development company that took streambed samples from many prospective area claims and, after classifying the sample down to a very small classified size, recorded and marked those samples for further analysis at a far away, specialty laboratory. He was looking for specific results associated with microscopic Gold which was associated with load deposits not easily visible on the surface.

Larger, visible sizes weren't what he was after, but rather the unique, tell tale indicator that a placer miner wouldn't usually notice. This system of "Prospecting" for un-noticed hardrock possibilities was a win-win situation since (against less than even slight odds) a "hit" could ultimately develop into a high dollar sale to an interested large, with deep pockets, mining corporation. Finder's fees and mega sales prices of the claim would benefit everyone, especially the claim owner.

Like you, Dick, Dan's samples just didn't make it to phase 2 in the process.

Mighty cool to learn about the system, having actually see it in action.

As to random or specific concentration sampling of sample dirt for obvious levels of visible Gold -- well isn't that what placer panning during the prospecting phase is all about

Joe

[Geowizard]

A prospector's intuition;

This doesn't support the narrative but the evidence from past and present GOLD prospecting seems to support the narrative that soils are used to point uphill/upslope to find lode deposits and not downhill/downslope to find placer deposits.

Being a good prospector is like being a good detective. We look for clues and make decisions on a course of action that will provide more clues. The movie, "The Treasure of the Sierra Madre" was not intended to be instructional. It reinforces a concept that has been understood and accepted by prospectors that goes back probably as long as humans have been prospecting. It's hard to say how many young prospectors watched this movie and developed a sense of direction in their lives prospecting for GOLD!

The Treasure of the Sierra Madre (3/10) Movie CLIP - Dumber Than the Dumbest Jackass (1948) HD

https://www.youtube.com/watch?v=_pWx7N8gSoY

Prospectors have to be keen observers. The process of using our observational skills combined with developing an intuition to look uphill/upslope for GOLD directs us to go in the direction of where the GOLD is coming from rather than postulating on where it went.

A discussion with Labrador Gold's Technical Advisor: Shawn Ryan

https://www.youtube.com/watch?v=YZ9IlsYw_Lk

All of this answers Slatco's question indirectly and may be the reason why we have not seen anyone chime in on having used soils to locate a placer GOLD deposit.

I would submit that most of the existing placer GOLD deposits of any significance have been discovered.

Here's why;

GOLD in relative abundance is known to exist in mining districts where the conditions were just right for GOLD to be driven to the surface and be discovered. Prospecting in all reaches of the World has been continuous for millennia. Enough prospecting has been done to make discoveries, mine out the economic GOLD resources and leave! In the process, "most" of the existing GOLD deposits of any significance have been discovered and mined out. Mining is being done today on the GOLD deposits that continue to remain economically viable.

For the prospector today, the pickin's are getting slim!

Where are the remaining undiscovered GOLD deposits?

Stick around and find out!

- Geowizard

[Geowizard]

Pieces of the puzzle;

When asking a question of this group and the group experience, the question may be viewed by many (millions) of viewers that are not members and therefore cannot reply. Considering the breadth of experience of the limited number of members of the group and the possibility one or a few might have relevant experience on a given topic really cuts down on the possible replies. The probabilty of a reply from a member having a piece of the puzzle is remote.

A second factor;

Miners and prospectors learn early in their experience to "keep it zipped". Sharing information on an open platform can be viewed by anyone on earth. Posting is a "Global" broadcast to whom-ever and where-ever the viewing public is and may reside.

Consumers;

Plain and simple, viewers are consumers. Viewers of this forum consume content and information related to GOLD prospecting and mining. Conversely, I enjoy sharing content that is informational and relevant to a given topic.

Public opinion;

Opinions are important. I avoid opinions including personal opinions because opinions are usually subjective. Objective information can be gained from scientific journals. In many cases, a citation is given on a sentence by sentence basis. Citations become leads to more pieces of the puzzle.

Information related to soils, soil sampling, and related subject matter can aid in our understanding of the dynamics involved in the question of erosion of GOLD and the eventual deposition of alluvial GOLD in placer deposits even though the pieces may not provide a direct answer.

Our experience is limited, however the World experience provides a rich resource of publications. Publications are available on a global scale to help us in our efforts to prospect for GOLD.

For example;

Morphological evolution of gold nuggets in proximal sedimentary environments, southern New Zealand

https://www.sciencedirect.com/science/a ... 6816303882

Learning about a given topic can be time consuming. Like solving any puzzle, time is needed to compile sources of relevant information representing the pieces of the puzzle and store that information in a file system where questions can eventually be answered.

Having others helping gather and arrange pieces of the puzzle can make the process faster in finding answers!

Stick around! There's more!

- Geowizard