Mercury (duh. . . . ). Get as much as you can, because it’s not very efficient. A neutron source. Ideally you need a particle accelerator (or a nuclear reactor). A neutron moderator. Water (yes, the stuff out of a tap) works pretty well. Neutron shielding, reflecting and collimating equipment Nitric acid
Ordinary mercury contains seven isotopes: Hg-196, Hg-198, Hg-199, Hg-200, Hg-201, Hg-202 and Hg-204. When it absorbs a neutron, Hg-196 becomes Hg-197. Hg-197 decays into gold. As a by-product, Hg-202 and Hg-204 become Hg-203 and Hg-205, which decay into thallium. Other isotopes change into each other and remain mercury.
Proton plus Hg-200 is one unfavorable (due to high positive nuclei charge and repulsion charge), yet with a possible alternate pathway.
And now for the bad news: Though Hg-196, the isotope is readily converted to gold as Hg-196 readily absorbs neutrons, it only comprises 0. 15% of natural mercury left. Assuming perfect conversion to Hg-197, then after one half-life (half of the Hg-197 decays), a kilogram of mercury will give you. . . 0. 73 grams of gold. That’s right, you get less than three-quarters of a gram of gold per kilo of mercury. To further increase gold yields and make better use of mercury, you can try to hit a isotope specific mix of Hg-198, Hg-199 (together 27% of all mercury) with high energy protons, kicking out neutrons. Yet this is an extremely inefficient process. Keep doing it until finally to converted to Hg-197, then wait just as above for decay to Au-197 or gold. Repeat nitrate steps
