Keep panning and sooner or later you'll find some mercury that more than likely will be attached to gold but it will be silver colored. Just small flakes for me but I have heard of people finding pockets of the silvery poison.
I have dug, I'm almost sure, three. The way to dig one is in a coin spill of wheaties and two of them will be stuck together and there will be whats left of one inbetween.
I've done that twice. The first was at a very old college campus and it was a bunch...like 15 wheat pennies. It was obviuse...
Nice! What would make you think that testing silver would give a positive diamond indication? My guess is that you did test the stone, otherwise you would for sure get a negative indication.
Grats and thanks for the share.