130 FEET! You’re ambitious tunnelers. Is this hard rock mining? I do
hope you have all your structural timbers where you need them.
Pyrite is a brittle mineral and gold is soft, malleable. Tapping with
a hammer will turn pyrite into powder, gold will flatten if it’s a
large enough piece.
Scrape a piece on the unglazed back of a ceramic tile; Gold will
leave a gold metallic line, pyrite will leave a black line. Try to
melt some of it into a bead of metal; pyrite won’t cooperate on a
small scale, and with enough of it you’ll probably get iron, not gold
(pyrite is iron sulfide) If it IS gold in a rich vein, you’ll get a
little bead of metal that’s yellow, very soft, and can be easily
flattened with a hammer.
That said, gold CAN occur in with pyrite in small but worthwhile
ammounts, giving “fool’s gold” substantial value, but the odds aren’t
very good if all you know is that the rocks are golden colored. I
believe most of the gold mined today is dispersed so finely throughout
the ore that it can’t even be seen with the naked eye. In that form
you’d need to smelt a ton of it to get anything measurable; a tenth of
an ounce per ton is a rich ore. Any ore in which you can see the metal
at all is VERY rich.
To be absolutely sure you’ll need a pro to assay the ore. Good luck.