Christian;
Its an interesting link, enough so, that I bookmarked it.
I did a quick read of the article on black sand, and I must tell you, it is wrong in several aspects.
1) It is right about the spiral wheels, I have a desert fox and its not as good as one I made, with a purchased, ready made, wheel (wheel and only a wheel) neither will separate flour gold, it has to be granular;
2) never use a magnet, as was suggested, you will lose any platinum, which is usually weakly magnetic and can have magnetite inclusions, also a large amount of Illmenite (semi to non magnetic black sand) will remain (Illmenite is titanium rich ore), fine gold can have magnetite bits and will go with the magnetite because of residual static electricity (which water stops);
I use a magnet, but not dry, I put some of the concentrate (a table spoon or six, with some water) into a plastic gold pan or a plant-pot bottom (green and smooth,) then, I have a big ring ceramic magnet off a big old woofer, which I rub, in a circular motion, ON THE OUTSIDE BOTTOM of the pan.
The concentrate CLOTS up, because the magnetite gets mutually semi magnetized, but not strongly enough to hold the platinum and certainly not gold.
Then I shake the pan a bit and I can begin washing off black (Magnetite only) sand because those little clots of black sand have a larger surface area and catch the water, better. (Into a tub, of course.)
When it gets down, to where I can see gold, I change to a different tactic, one I cannot describe in a way anyone would understand.... IF I could do a video, it might work. Its a technique I saw an old Sourdough use. His remark to me was that he expected I knew all about it.... well, I kept my mouth shut and my eyes open, for once. But it takes practice.
My magnet method is better than a spiral pan.... the ONLY thing I found a spiral pan good for, is a concentrator, right on the gravel bar. Power, you ask? Solar panels and a small lead-acid battery. And no clouds. (The wheel has to be set closer to horizontal.)
Concentrate is not a big problem: when I pan or clean up a sluice, I crudely concentrate it, if it gets too bulky, I fine down the concentrate, making sure only the non-black sand goes over. (All the time, into a rubber tub.) Then I take everything home to play with, where I can re-work it as much as is reasonable.
I have never found any gold in the stuff I washed over, after using a magnet as I described, but I have found gold, with the dry method.
The site is worth looking at, even reading, but dont take every thing as Gospel. Experience is a great teacher.
Brian AKA goldigger
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