Iron Oxides as a Visual Prospecting Clue (Part 2)
(Shear zone with quartz "lenses" angling up through the zone.)
Once again, the presence of significant iron oxidation in rocks, vein materials, or even wash or stream placer sections can often indicate the presence of gold. Just how much gold is influenced by a range of factors.
These factors include the degree of mineralization and oxidation present and, in the case of lodes, veins, or outcrops (what the Aussies call "reefs"), whether shear or contact zones conducive to gold formation are present in the immediate area. If you're not well versed in gold geology, let me explain a bit about shear and contact zones.
Shear Zones tend to have a tabular or sheet-like structure that's made up of rocks that have been placed under higher strains or stresses than the rest of the country rock in and around the shear zone itself. The image at the very beginning of this post is a good example of a shear zone.
Contact Zones are basically where two diverse geologic formations meet or come into "contact" with one another.
If heavily iron oxidized materials are part of either of these zones the potential for gold mineralization may be be increased significantly. That stated, you should take your time examining and sampling areas like this out in the field.
(Oxidized contact zone where the zone is surmounted by a different geologic formation.)
Another important type of potentially gold-bearing material are laterites. Those of us living here in the Northern Hemisphere aren't likely to come across these iron-rich or iron-oxide rich soils or gravels because they tend to be found in mostly wetter, tropical or sub-tropical climates.
You Aussie "fossickers" and nugget hunters who've spent time in the Outback know what I'm talking about here. You've had to deal with the heavy iron content contained in these rusty red looking soils and gravels, some of which still possess excellent gold values.
Here's the Lesson
I'm not a geologist by any stretch but I was mentored in my "newbie" prospecting and mining days by old timers who knew what to look for when it came to gold. If you're serious about mining and prospecting and want to increase your chances out in the field, then it's a good idea to learn to see (and hopefully understand) the visual clues I'm talking about here as well as many others I haven't discussed yet.
One thing you need to understand here is this: not every geologic contact or shear zone is going to contain gold, or even be heavily mineralized for that matter. So don't waste your valuable prospecting time trying to turn sows ears into silk purses in locations that are NOT conducive to gold formation or mineralization.
(Gold-bearing laterites are found in many Australian locations, including this area near Mount Magnet.)
Some of you out there may be thinking that you don't need this sort of information to find a bit of gold and maybe you don't. Hell, there are numerous locations I could go to with a gold pan or sluice box and recover some color too. There's not much challenge in that sort of approach in my mind though.
The lesson here is this: gold prospecting and mining is a work in progress...you can NEVER know too much about it all. There is always more to learn and the more you learn the more proficient you'll become. The more knowledgeable and proficient you become, the more those "golden" opportunities will come your way. In the end, the more gold you'll get.
Humming the Same Old Tired Tune
Unlike the bulk of those gold prospecting and mining "experts" or dream merchants out there (online or otherwise), I have no vested interest in selling you anything or trying to get my ticket punched at your expense. What I am attempting to do in this post (and in "Bedrock Dreams" as a whole) is to pass along info that can help you follow in the footsteps of the old timers whose knowledge and expertise of the finer points of gold prospecting and mining is rapidly becoming a dying art.
Like my two mining mentors however, what I am doing is passing along info, tips, and a philosophy of prospecting and mining that can help you rise above the pack while the rest of the experts are pretty much humming the same old tired tune while they try and lift another buck from your wallet. If you've been with me for a while and haven't realized that yet, then I guess it's my bad and I need to work harder to bring you into the fold.
Learn More and Keep Learning
Am I a hard ass? Yep. Am I opinionated? Yep. Am I the best out there? More than likely not, but I'm better than most and more importantly, I truly care and that should count for something.
My main goal as a miner, writer, and blogger is to help you become the very best you can be in each and every regard possible. So take the time to learn more and to keep learning all you can about gold formation, geology, deposition, mining gear, approaches, methods, techniques...anything and everything related to mining and prospecting. And, while you're at it, try to become a better person at the same time. Can't hurt you...
Finally, stay away from the "quick fix" mining shysters and become a modern version of what was best about the REAL old timers. Why? One day you'll be standing in my shoes and I expect you to "pay forward" what I've taught you.
If you liked this post, you may want to read: "Iron Oxides as Visual Prospecting Clue"
(c) Jim Rocha (J.R.) 2012
Questions? E-mail me at firstname.lastname@example.org