(Even you old sourdoughs could learn a thing or two here.)
In this post I'll continue to answer Dominican Republic (D.R.) gold miner Eduardo Herbert's questions dealing with prospecting, mining, and gold detecting. Stick around because the information I'll present here has something for everybody out there, greenhorns and old sourdoughs alike.
Eduardo asked me about using a metal detector or other electronic means for trying to trace the path of the coarser, more porous gold he's been finding in the D.R. Sierras. Again, a friend of Ed's suggested that gold (which is unlike most of the placer gold Ed's recovered in his dredging operation) may be eroding out of a vein or lode and that he and Ed should look for that source. This is pretty good advice in light of the coarse gold versus water-worn gold issue. I've never been to the Dominican Republic (although I'd love to go there sometime) but based on what I've seen in photos and travelogues it appears to be pretty lush with plant growth, if not downright dense in certain areas. Now higher up in the D.R. Sierras I suspect that the overgrowth factor may lessen or otherwise change somewhat, but only Ed knows that for sure. Whatever the case, heavy overgrowth of any sort is going to be problematic from a gold prospecting standpoint. It makes the "eyeball" factor much more difficult and wielding a metal detector an exercise in futility in certain circumstances. Ed's Minelab GPX 5000 is an outstanding gold machine but his experience with it is limited. I suggested he buy and mount a larger search coil on it if he wants to try and trace or locate vein material. Elluvial gold (or alluvial too, for that matter) can still be detected pretty easily with the larger Minelab coils although metallic trash becomes a more prominent issue. The larger coil gives greater depth penetration not to mention the fact it can cover more ground per sweep. Additionally, Minelab gold machines have gained a justly deserved reputation for their ability to handle heavily mineralized ground and hot rocks, even in the exceptionally iron-laden (oxidized) goldfields of Australia's Outback. Another alternative I suggested to Ed from the detector standpoint was the possibility of using a double-coil deep seeker unit like the Garrett "Treasure Hound" or the Whites TM 808 (or any other reliable brand). These units are primarily for use in relic and treasure hunting, but if you're looking to detect much deeper down for ferrous or non-ferrous metals, these machines can do the job. Again, the main bugaboo here for Ed is his relative inexperience with these machines which, of course, take a bit of time to learn to operate efficiently and effectively.
(Also called a "double box," two-coil deep seeking detectors like this Whites TM 808 can be effective in gold prospecting and relic and treasure hunting.)
One thing Ed mentioned in the gold prospecting regard was the idea of purchasing a precious metals locating unit. Now let me tell you all something that many of you have heard from me in the past. When I hear the words "treasure locator" or "long-range gold locator" my mining and treasure hunting hackles go up. Why? Because most (if not all) of these units are based on total fantasy (i.e., BS) and the dream merchants who purvey them are little more than scammers in my book. There, I said it. Now I'll sit back and await the onslaught of e-mails or comments from those who firmly believe in a "locating rod's" ability to detect and pinpoint treasure stashes or gold veins from 50 miles away. Hit me with your best shot, go ahead. But you'll never convince me otherwise. So Eduardo, as I mentioned to you already, forget that idea. It will only take money out of your own pocket and put into someone else's with no real value added. On the other hand, the idea of using a hand-held magnetometer or ground-penetrating radar unit for detecting buried anomalies in the prospecting process holds real value. The problem here for Ed is cost and, once again, experience in using these units and deploying them to good effect out in the field. Gold prospecting for veins, lodes, reefs, or blow outs is not an easy task in the best of circumstances and with all the circumstantial factors already discussed, Ed and his friend have their work cut out for them. But miners never let the little details stop them...and never will if there's gold to be found.
(A long-range gold and silver treasure "locator." And Santa Claus and the Easter Bunny are real too.)
Another question Eduardo asked me was why some of the placer gold he was recovering from dredging bedrock was heavily stained or colored as opposed to the bright yellow, lustrous gold he normally recovered. In asking this, Ed mentioned that the bedrock where he was recovering the "stained" gold was also colored in a similar fashion. What this suggests to me is, of course, the presence of oxidation...more than likely iron (FeS2) oxidation. Since the gold was in contact with that section of bedrock (laying atop it or within its cracks and crevices) it was stained by the very same oxidation coloring the bedrock itself. For those of you who may not know this, gold is not impervious to staining from contaminants, despite its long-term durability. Over the years I've recovered both wet and dry (desert) placer gold that was heavily stained by iron or copper oxides or even manganese (which made the gold appear dark grey or black). Most of this oxidation on wet or dry placer gold seeps into the small cracks, depressions, or other anomalies on that piece of gold's surface but I've also seen it cover a good part of the surface itself as well. Don't worry about any oxidation on what you recover Ed because what you hold in your hand is still gold and still as valuable as the rest of the gold you're recovering. You can also clean that oxidation off using various means but I always liked a bit of oxidation on my nuggets or larger pieces of gold...gives them a unique look. Additionally, those oxidation colorings may hold clues to the gold geology that you're presently working and could, if analyzed carefully, lead you to that lode or vein.
(Slightly iron-oxidized nugget from Wales. Note how the oxidation is inside the depressions and irregularities of this piece.)
Eduardo continues to kick butt dredging (I've seen his latest gold recoveries, by the way) and is a miner's minero, that much is for certain. At the same time, he's humble enough to ask for help when he needs it and that's a true mark of personal character in my book.
Best to all and a hearty bueno suerte to Ed!
(c) Jim Rocha (J.R.) 2016
Questions? E-mail me at firstname.lastname@example.org