Comments by "David Himmelsbach" (@davidhimmelsbach557) on "FIND GOLD in ROCK'S - Geology 101 | ask Jeff Williams" video.

  1. Below a critical size, Gold -- or any metal -- looks Black. (Carlin deposits are the classic example of a gold deposit that can't be seen with the naked eye. With Carlin gold, the shiny is trapped inside a sheath that hides it. You have to mill the ore first and then you can assay it.) But, it's also the case that ultra-fine free mill Gold will look Black when it's riding with magnetite and other iron ores. By ultra-fine I mean gold so tiny that you HAVE to use a micro-scope or chemical assay means to detect it. Even so, like Carlin gold, the total amount can surprise you. When the Gold first rose to the surface -- probably in a pluton -- then off into some dike -- its absolute concentration would be amazingly low. It took complex geo-chemistry for it to re-concentrate to the point that pickers and nuggets were formed. But it stands to reason that only a fraction of the ascending gold ever 'condensed' into visible gold: nuggets, pickers, flakes,... The larger the nugget, the slower the condensation process. Some hefty nuggets figure to have taken millennia to crystallize out. Assuming this is the case, one is well advised to take a second look at magnetite cons. The cyanide process ought to be spot testing such heavies, to see if anything is getting by. Further, the tinier the gold flake is, the more it stops behaving like gold. It starts to float on water -- surface tension -- and it goes much further down stream than you'd expect. It just refuses to behave like the heavy metal that it really is. What this means is that should you find a pay streak -- especially in a dry (desert) deposit look further 'down stream' and sample the magnetite to be found there. It figures to look blank to the naked eye -- even a jeweler's loupe, while still having enough gold to react with NaCN solution. Like anything, results will be hit or miss. Just remember that the Carlin deposit is the largest play in the USA right now -- and stood undiscovered for a century -- because each particle required a microscope to spot, and milling to even begin an assay. It's now thought that there is more Carlin gold than any other deposit type in the Western USA. The big hang-up being that the rest of the play figures to plunge DEEP under overburden. Hey, maybe robots will change the mining equation. They tend to be so brave.
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