Interpreting Visual Prospecting Clues: a Dying Art? (Part 2)
(Old timers back in the day in southeastern California's Rand Mining District.)
Although the tips I'm giving you in this series of posts probably have a stronger connection to hard-rock gold prospecting, they are also applicable to placer mining. I guess the rule of thumb here is "knowledge is power." So let's see what other visual clues to mineralization the old timers looked for.
Prospecting and Mining
First off, let's clarify things a bit. Although many out there (including some of the self-proclaimed experts) view gold prospecting and mining as interchangeable, I was taught by my old timer mentors that they are, in fact, two distinct entities in many respects. I've said it before so I'll say it again now...gold prospecting is the art of finding gold and gold mining is the art of recovering it.
Without naming names (since I seem to get pilloried by fans and cult followers each time I do), I think some of the TV gold mining shows that are so popular right now are classic examples of the difference between prospecting and mining. My contention is that you could take just about anyone with minimal mining experience and put them on proven gold ground with decent equipment and minimal instruction, and they'd be able to pull some gold...even if those recoveries were essentially "blind" luck.
Quite a Feat
On the other hand, ask any one of these inexperienced folks to go it alone and actually prospect for gold (hard rock or placer) and I suspect they'd be standing there for days or weeks just scratching their heads and waiting for the excavator, skip loader, and wash plant to show up. In other words, they probably couldn't prospect their way out of a wet paper bag. So again, it's one thing to pull gold from known gold ground with others pointing the way and it's another thing altogether to see and understand the visual clues that will bring you to that very same gold. Make sense?
Gold Prospecting Books
Anyhoo, many of the old time gold prospectors and miners were true artists when it came to interpreting Mother Nature's visual signs. For starters, without any scientific basis whatsoever for their knowledge, they were still able to find the yellow metal using their eyeballs. That's quite a feat...especially when you consider the old timers were finding precious metals this way long before the advent of metal detectors, ground-penetrating radars, or geo-physical survey equipment.
What they knew and how they did what they did should not be forgotten. That's why I'm trying to pass along some of their "art" to you. So here are a few more visual clues to consider:
3) Abrupt changes in color in the earth and country rock
One of the most significant visual clues out there is color. No, not "color" as we like to call trace gold, but the coloration of terrain and country rock. The old timers knew (either intuitively or through experience) that abrupt changes in the color of the earth beneath their feet and in the country rock surrounding them often heralded the presence of mineralized zones. When passing through these sorts of areas or zones they would closely examine any and all physical clues around them and sample low-lying areas or, alternately, float or potential ore.
(Did you notice both vegetation and color changes here?)
What sorts of colors are we talking about here? The yellows, reds, blues, greens, oranges, purples, or other colors that might signify the presence of metal or mineral oxides or sulfides. These were huge visual signposts that the old timers kept a keen eye out for, especially here in the American West and Southwest. If these colors were associated with quartzitic or alternative types of float, all the better. This sort of visual clue told the old timers that gold, silver, or copper could be lurking about and if it was, they were going to find it.
The Real Trick
Let me digress for a moment here. There's a common misconception among many small-scale and weekender gold prospectors and miners today that the presence of quartz is the most significant visual clue to the possibility of gold. While this is true in many instances, in just as many others the presence of quartz or quartzitic rock doesn't mean a damn thing as far as precious metals are concerned. Ever hear the term "bull" quartz? The old timers used it derisively to describe white or clear quartz that was essentially sterile in terms of gold or silver or other metals.
As a matter of fact, there were probably almost as many gold, silver, and copper mines discovered in the West and Southwest whose metal-bearing matrix was not quartz, but something altogether different. Yes, you should keep an eye open for quartz, especially if it shows the coloration of heavy oxidation. But the real trick is to "see" where mineralization is occurring around you. This brings us back full circle to Visual Clue 3).
There's much more to what the old timers knew and practiced, and I'll cover some of that information in my next post as well as providing you with more visual clues. In the meantime, stay safe and keep smiling.
(Note: Miner Miles C. sent this link along for "De Re Metallica," a very old treatise that contains some very good information on the topic at hand as well as mining in general. You'll have to fight through the archaic language, but it may prove worthwhile.)
(c) Jim Rocha (J.R.) 2013
Questions? E-mail me at firstname.lastname@example.org