Wednesday, August 14, 2013

Interpreting Visual Prospecting Clues: a Dying Art? (Part 3)

(Gossan outcropping.)

This post is the third in a series about the visual clues the old timers looked for when prospecting for precious metals. There's more to be learned about this topic, so read on.

What Drives Me Crazy

You know, it's easy to view the old-time gold prospectors and miners in a somewhat romanticized light. Yes, many of them were exceptional people with exceptional skills and abilities, but just as many others were drunkards, compulsive gamblers, and just general "n'er do wells." People are people after all, despite the uniqueness of their personal occupations or avocations.

What drives me crazy sometimes about the old timers was their penchant for consistently finding the gold, moving on without fully cashing in on their own finds, and allowing others to become filthy rich off those very same finds. The famous desert rat prospector "Shorty" Harris was a classic example of this type of old timer. I know of other old timers who simply drank or gambled their newly acquired wealth away as quickly as they could.

Deep Need?

Character flaws? Perhaps, but I think this sort of behavior on the part of many old time prospectors and miners constituted a deep need to be free in the truest sense of the word. Granted, they moved about in a much "freer" world in their day and age, unencumbered by today's bureaucratic restrictions and selfish standards. But perhaps I too am falling into the trap of "romanticizing" these things.

Gold Panning Kits
Gold Concentrators
Metal Detectors
At any rate, there's no doubt the old timers lived a hard life in many respects. A life not well suited to couch potatoes, wannabes, or those totally dependent on others to find the gold for them first. The old timers knew what it was like to to sleep on hard ground, to eat out of a can while battling heat, cold, wind, rain, and snow, and to bust their asses day after dreary day...all the while keeping their eyes peeled for Mother Nature's visual signs and heeding what she was telling them.

4) Rotten-looking quartz or other "host" material that crumbles or crushes easily

Often called "blossom rock" if it contained visible gold, the old timers were quick to "eyeball" this sort of material and after visual examination; crushing it, panning it out, or having it fire assayed. Known in geological terms as gossan, this material displays intense or significant oxidation (typically by sulfides) and is highly weathered or decomposed. The old timers knew (either intuitively or through experience) that any material undergoing this much geological or environmental change had a high probability of containing precious metal and that any float or outcroppings showing these characteristics could spell "j-a-c-k-p-o-t!"

 (Gossan or "blossom rock.")

I've had the good fortune to come across gossan out in the field on at least two occasions in my own checkered gold prospecting and mining career. What I remember the most about it was its deep, nearly solid coloration (in my case a very rusty reddish-orange), its odd, "spongy" texture, and how easily it could be crushed or even crumbled by hand. Sadly, the gossan I found wasn't carrying much gold but it was carrying a little, so if you ever come across something like this in your prospecting and mining journeys make certain you check it closely. Common gossan colors are the reds or reddish-oranges of iron oxidation, yellows, and even dark blues, greys, or black. These latter three colors may signify the presence of copper, silver, or manganese.

The visual interpretation rule of thumb: "If it looks different or odd, take a closer look."

(c)  Jim Rocha (J.R.)  2013

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  1. Jim, as always, very interesting. I've seen some very rusty looking rocks around here, but they don't seem crumbly. Should I pulverize them and pan it anyway? The few I have, haven't shown any color. As for the old timers moving on, I'm a big fan of the poet Robert Service. He hit the nail on the head when he wrote "It's not the gold that I'm wanting, so much as just finding the gold." There is something about the thrill of the chase, after you find it, it's just work! Gary

  2. Once you see gossan there's no mistaking it Gary. Rust color alone (iron sulfides) will not mean it's gossan...has to have the heavy weathering, spongy looking, decomposed/crumbling thing going on (for the most part anyway). However, any host material that is HEAVILY iron stained or oxidized should be examined closer. Best, J.R.