Hard to tell from the picture as it's kind of small, but is there any oxidization on the rock? When exposed pyrite typically is associated with a lot of rust from oxidization. See attached picture for oxidized pyrite at the Devonian/Mississippian unconformity.
Also, does the portion of the rock in question have distinct crystal faces? Like is it square, octahedral, etc? That's a distinguishing feature of pyrite if so.
A couple of other things you can try: Try scratching it with a knife, gold will scratch, pyrite will not; When you scratch it if you smell a sulfur odor (rotten eggs) when you put your nose right up to the rock, it's pyrite.
Love the history lesson though!!