Well,I didnt want to tell to much to prying eyes,but I have stated it before and its not that uncommon,but my average season dredging used to produce anywhere fro 5-15 POUNDS of mercury,as said nearly every water way in the gold fields has mercury,the only way to remove it is suction dredging.I hate it.....it has its place but not in the field...but its there, always ....more often than not has gold in it,it has to be burned off either through a retort or by Nitric acid,both can emit toxic fumes and leave toxic residue that can be absorbed through your pores......the toxic fumes smell like burnt almonds so there you know what it smells like.......I know,yea,not good,have been through all the testing too,not fun,35 years around it though,and I am not dead,dont sweat the panning/you are in no danger.Many on here myself included used to shine dimes,put it in our shoes,pack it around in my pocket(in a vial)its not Satans brew...but has to be respected
also as Terry stated it is naturally occuring as well....