Not sure I’d trust this myself as gold often gets picked up stuck to the black sand and I’m sure this would just launch the excess into orbit!
Yeah. Better to have magnets in a classifying sluice / gold cube.
I use a magnet under my plastic pan. sucks up the easy stuff. and then carefully wash through the magnetic dregs under a bright light to make sure I’ve got it all. anything my eyes can’t see due to size will get missed though. I don’t like loosing even the tiniest of specs. fussy