(Got a killer dose of sunburn just above the bum crack bending over in the stream with my pan, a reminder sunscreen has to go EVERYWHERE.)
It also alloys easily, i.e. it is dissolved, with other liquid metals, e.g. silver, copper, indium etc., but that is less obvious than with mercury, because those metals must first be heated to great temperatures, to become liquid, before dissolving gold.
The relation with arsenic is different. It is an affinity between ionic gold and arsenic, not between metallic gold and arsenic.
The gold ions are very big, among the biggest metallic ions. Because of that, the gold ions have great affinity only for some big anions (negative ions), i.e. for the ions of arsenic or of tellurium, which have approximately the same size.
This is in contrast with the smaller ions of silver and copper, which have great affinity with the smaller anions of sulfur.
It is well known that the gold ions have the greatest affinity for the anions of the size of arsenic and tellurium. Tellurium has an even greater affinity for gold than arsenic, but tellurium is extremely rare at the surface of the Earth. Due to the rarity of tellurium, even if minerals with gold and tellurium are well known they are less frequently found than those were gold is associated with arsenic.
While the maximal affinity of gold with tellurium and arsenic has been well known, this research has elucidated details of the mechanism how this creates arsenical minerals rich in gold, which may help in the prospection for such minerals.
Because gold is normally much more scarce in the environment than arsenic and than other metals with which arsenic combines easily, the minerals with arsenic and gold are seldom straightforward combinations of arsenic and gold, but as explained in the article, gold infiltrates arsenides of other metals (usually of iron, whose arsenide is the most abundant).
Gold can be created through an unrelated process of nuclear transmutation, but it's impractically expensive [0].
[0] https://en.wikipedia.org/wiki/Synthesis_of_precious_metals#G...
Nuclear reactions WILL produce gold - in many ways actually (none profitable afaik):
- throw a neutron or 2 at neighboring elements, ensure they have the right energy for the cross section, hopefully with neutron capture and beta decay you get some gold (maybe the stable Au197 version, maybe a violently radioactive isotope though, I wouldn't wear a ring made of that. And it will eventually stop being gold when it decays). Oh an immense amount of radioactive byproducts. And the starting elements are often more expensive than gold itself.
- Fuse 2 lighter elements with just the right weights, you may get gold. But creating elements above iron is energy-negative so your fusion reaction will immediately die unless you can sustain it. All the gold we found on the planet was created during supernovas IIRC.
- Fission something heavier and hope that gold is one of the pieces you're left with.
- Start with an unstable isotope of Thallium, Bismuth, etc and hope for a few alpha decays to line up and get you gold.
There are actually quite a few paths.... and ALL the gold you'll ever see, whether artificial or "natural", was created with one or another (but most really is from supernovas). Remember, we started with only the building blocks in the big bang, mostly Hydrogen.
It's like if the federal government allowed you to print your own money but only if it was ones and it turned out that it cost $100/bill to do it properly.
Gold could be made by neutron capture on Hg-196. This is a rare isotope, so doing so would require two things: cheap neutrons, and a cheap way to enrich that isotope.
Helion's FRC scheme could provide the first if operated on DD (even if just at engineering breakeven). As for the latter, there's a scheme that's been proposed for mercury isotope separation that exploits the change in magnetic moment of mercury atoms when they are optically excited. This would use radiation from a mercury lamp that itself uses isotopically separated mercury to produce radiation that would selectively excite just that isotope, and steer the atoms in a beam using a magnetic track.
(This isotope separation technique has been proposed as a way to make fluorescent lights more efficient by reducing UV photon trapping in mercury vapor.)
The world's mercury production is low enough and this isotope rare enough that this wouldn't affect gold prices.
The processes involved are so expensive to do that in terms of cost it doesn't really matter what you are using as the source material, and the way gold is very resistant to corrosion is useful for using as a target in experiments.
