Hi, not sure if this thread is even still going but I have a similar problem. We sent some samples to a laboratory for testing. Aqua regia came back at an average 60 g/t Au (this material is a tailings stream at a gold mine). However when we tried to get a vaguely similar result in a leachwell/AAS assay it came back at 0.3 g/t Au (I was understandably sad!). I then went and ran an AAS assay on the primary black dirt from our Gemini table. This came out at 3.5 g/t which I know to be wrong. That 20kg of black dirt is from a ton of material and will yield maybe 15 grams of gold. That’s not as assay, that weighing it in the lab. So the grade of the black dirt in in excess of 750g/t Au. But why did the AAS machine say 3.5 g/t? It was only calibrated to 20ppm but should have gone crazy.I used a REM lowered very slowly over the Gold/ other minerals, dry, very slowly, until I could see some material being lifted. At this point the magnet was held in position at 3" above the cons. The pan was then shaken on the flat surface. At no time did the magnet get closer than 3 ". The result was such that if you can imagine the results of when Dan just stuck the magnet into the pan, in his video, and pulled it out full of black sand with a little bit of trapped gold, exactly the opposite happened. The mass on the magnet was 99.9% gold, with a little black sand. This is no fish story. I wish I had a camera to take a pic so others would believe this. I still can't believe what I saw.
After all of this a friend of mine rolls up to help. With some hot HCl the gold appeared from the material like a gold paint in the pan. Super fine, so much so that it floated - so fine it didn’t overcome the surface tension of the water.
Point is things are never as they seem and gold is very tricky. I’m now going to mess around with some magnets as well!