Noticed this was your very firsts post - so, Welcome Aboard Louie! You didn't list your state (or country) in your profile. So, you might consider jumping over to Sub-Forums: Select Your Area.... for information (i.e., clubs, hunts, finds, legends, maps, etc.) directly related to your state (or country).
Here's what is reported to be a good test for distinguishing actual Gold versus Fool's Gold (a.k.a. Iron Pyrite). Use a hammer on it. If it bends, it's gold. If it is brittle (breaks into pieces), it is Fool's Gold.
Probably pyrite if I remember correctly it is commonly found with quartz and being that large odds are its not a nugget, there are many tests to tell the two apart some are very simple but I can't remember them but Google could help you with that