Working on the tailings of the same sample from above with a loupe I could still observe micro gold. I used mercury to pick up the fine gold in the original sample by panning. The mercury wasn't picking up all the gold the color of the gold was off it had a bronze haze. So as an experiment I poured a little phosphoric acid into the white sands and let it soak overnight. Rinsed with clear water today and panned lightly and nice line of gold appeared added a drop of mercury and the gold started attaching. Apparently, the gold had a little iron coating / staining I'm careful with the mercury and all my samples are retorted. A few photos with my phone you can see the gold floating on the mercury ball and a macro photo of the micro gold. I save all of my tailings for this reason when I get a quart jar full, I treat it with acid my mini leach.