“Gold doesn’t oxidize!” - Well, when you just leave it expose to the air, it doesn’t, indeed…
…however, a recently discovered fungus happens to happily oxidize gold.
And, where is that fungus from? Why, Australia, of all places!
Damnit, Australia… Wasn’t it enough to be a vortex of poisonous and murderous creatures, from exploding trees up to most of the most poisonous snakes in the world, not to mention drop-bears, that you now have to go and start tarnishing gold itself…?