I know a couple of fine-gold tricks: Add a little CLR (from Home Depot or Lowe's) to your black sand cons and swish it around and let it sit for about a week. Pour off the CLR and rinse the cons with fresh, clean water and recheck for "gold". Also, I've heard you can dry the cons, add table salt and cook it in the open air (don't be breathin' Mercury!) and this will sometimes bring out the flour gold.
Be sure to inspect the black sands as you clean them off the bottom of your magnet, as small bits of gold can be trapped and lost in this part of the process. Once you have removed nearly everything but the gold, use your magnet and stir the material at the bottom of the pan to pick out the remaining fine textured sands.
The amount of any truly “locked in” gold can be scientifically determined by very meticulously recovering all the free gold possible from a sample of black sand, making sure to carefully examine it under 10x magnification to see that all the free gold has been removed, and then take that clean black sand and run a standard fire assay on it.
Black sand may be generally defined as a constituent of “alluvial” gravel consisting mainly of fine particulate grains of heavy, dark colored minerals and rocks. These alluvial gravels, chiefly concentrated by wave, current or surface action, may also contain “eluvial” material that includes black sand
20-01-2019· "BLACK SAND RECOVERY" Heres How You Do It Getting upto 99% of your Gold out of the Black Sand Concentrates 1,[FOR STARTERS] What you'll need to process Black Sand Concentrates. one #12 classifier one #20 classifier two gold pans water wash tub few 5 gallon buckets. micro sluice or gold wheel tumbler Keene Gravity Bowl 2, Your first few steps.