If I remember correctly, I was at the DeYoung Museum in San
Francisco, looking over a display of pre-Colombian central and south
American gold pieces.
The explanations of process had me spellbound. Lots of heating,
etching, and scrubbing were needed for the surfaces, which were
beautiful, even in the present day.
For chemicals, the sources were both insect and vegetal. I can't
remember any Latin names right now, but you might start with known
poisonous species. If it makes you sick, that's probably the stuff
Almonds and their relatives are supposed to have trace levels of
cyanide. Hopefully, cockroaches may be high-yielders of the desired
As for scrubbing abrasives, harvesting is risky for sure.
Crocodilian dung was the source of fairly controllable particle sizes
of grits. Perhaps an eccentric in a big city has a crocodilian pet.
What with leash laws and pooper scooper rules, you might just get the
stuff at the lowest possible expense and bodily risk.
---best, Dan Woodard