Iron Oxides and Gold Pockets (Part 1)
Nature provides many natural clues to the potential existence of both placer and lode gold. In a general sense the most significant natural indicator is iron oxide. Even more significantly, visual indications of iron oxides in gold areas can lead to gold pockets and excellent gold recoveries.
Good Ol' Rust!
Those of you who've been with me for a while now know that I've talked about iron oxide as a visual indicator more than once here in Bedrock Dreams. But I've only alluded to its importance in locating gold pockets. So let's examine this connection at length. First, what is iron oxide? It's simply a chemical combination of iron and oxygen (FeO). Or to put it simply...rust. Iron oxides can be the result of either natural processes (for example, oxide ores) or man-made ones (iron "trash" like nails, screws, wire, pieces of scrap, and so on.). This is pretty straightforward and most of you with experience as prospectors or small-scale miners know what "iron staining" is and its unique relationship to gold, especially lode gold. But man-made iron oxides (again, iron junk) can also lead you right to the gold in placer environments as well. Whether natural or man-made, iron oxides are something your eyes should be looking for anytime you're out in the field.
Not a Winning Lottery Ticket
I'm on a slippery slope here because people with little experience as gold miners or prospectors (or those living in non-gold mineralized areas) tend to go ape shit when they come across rocks indicating any level of "suspected" iron oxidation near their homes or on their property. They'll take what I say here and then assume anything (rocks, earth, gravels, sands, etc.) they come across that looks reddish-orange or "rusty" means they may have hit the "big one." You know, the Mother of all Motherlodes. Then these good folks bombard me with e-mails and digital photo attachments of their "finds," asking if they've struck gold. You know the routine because I've harped on it before...the "Do my rocks contain gold?" syndrome. So let me get this out into open air once more. Iron oxidation (natural or otherwise) of and by itself DOES NOT guarantee you've stumbled across a gold deposit (lode or placer) nor does it present an airtight case that those rusty looking rocks in your hand have gold in them. Iron oxidation is simply a potential visual indicator, not a winning lottery ticket. This is especially true if you live in a state or province where there is no historical record of gold geology or gold mining. If you're a newbie or greenhorn and are reading this post right now, I ask that you PLEASE reread this section until you understand its core message fully and completely. For my sake and yours.
The Common Thread
OK, back to iron oxides and gold pockets. What's a pocket? It's simply a collection or aggregation of either placer or lode gold. Pockets are usually contained within a very small area and can vary widely in terms of the type and a amount of gold in them. In placer areas they usually contain a mix of fines, flakes, coarse gold, and yes...nuggets. In lode gold pockets you may find pieces of ore, nuggets, and chunky gold with pieces of matrix still attached to it, as well as smaller "fragments" of gold that have eroded out of vein material. Both lode and placer pockets can produce good gold amounts ranging from grams to ounces. In fact, the best lode pocket I know of produced over 30 troy ounces of gold (hell yeah!). I've never found or heard of a pocket that good in placers, but a nice pocket in a stream or dry wash has multi-ounce possibilities and, at the very least, multi-gram potential. Whatever the case, pockets are good producers of gold...including those elusive nuggets. Now I'm not talking about these finds in relation to any sort of commercial mining enterprise, I'm talking the average Jane or Joe small-scale guy or gal. People like you and I with a reasonable amount of prospecting and small-scale mining experience and knowledge. In fact, I know of some small-scale miners here in the West (and Southwest) who do nothing else but hunt for pocket gold. The common thread among these astute folks is that they use iron oxidation as their main visual indicator, despite the variance in their approaches. I will say this though...those who hunt for gold pockets in and around old lode mine areas tend to recover the most gold. Just saying...
Apples and Oranges
The gold deposition characteristics of placer and lode pockets are like making comparisons between apples and oranges in terms of taste and color. They are two different things even if they are both varieties of fruit. You already know how placer gold tends to get deposited in general terms in streams and washes. These are the "usual suspects" like behind large obstructions, along inside bends, in bedrock cracks and crevices, and the like. There are no real deposition physics associated with lode gold pockets though. At least not in the same sense as placer pockets. But again, the connection here is that they can both be found using iron oxidation as the main visual clue in terms of where you want to start prospecting or digging. Again, simple iron "rust" visible in streams or washes, or alternately...iron oxidation in "float" or exhibited in vein material and/or country rock.
Do I have your interest now? Good. There's more to come so stay tuned.
(c) Jim Rocha 2018
Questions? E-mail me at firstname.lastname@example.org