I wonder from my prospecting experience in VIC gold fields and...

I wonder from my prospecting experience in VIC gold fields and gem fields in QLD , gravity plays a big part in getting results .
My new question is about the ore nature here , are the gold particles easily detached from the lode material .are they fine or course , if coarse would move the lowest point when collection mixing is done . If the person doing this job is unaware of this, samples may be inaccurate .
If coarse, would a metal detector of some sort be able to check field residual for larger bits .???

A previous poster actually said that about being metal detecting ground ?
Perhaps a new field checking device like the VRS used else where is needed , just for gold .??

cheers