Richard, Hi, have been following all your posts here with great interest. I gather numerous ore samples from various sites when I go to Colorado prospecting. I bring these home to crush and test. The oldtimers really did throw the baby out with the bathwater most of the time. I've gotten several ores with good values but like yourself I have also found the same problems with separation of values from black sands when the material is really fine/microscopic. I have spent a lot of time experimenting with mechanical separation with ery little luck so I've always had to come back to using chemical processing (amalgamation, acids, leaching). These methods are inherently dangerous and tricky but give the most economical recovery of values for time and effort spent. I guess you should really get your ores assayed to find out if they are worth the trouble to process, unless you're just having fun experimenting, when you can't be out in the field. Good luck and hope you find lots of color.