Processes involving water often collect similar chemicals from a wide area and drop them in one spot. Also (and this was a big one for my understanding) fractio

Processes involving water often collect similar chemicals from a wide area and drop them in one spot. Also (and this was a big one for my understanding) fractional crystallization can help organize things: https://en.wikipedia.org/wiki/Fractional_crystallization_(geology) https://en.wikipedia.org/wiki/Fractional_crystallization_(ge... I'm not sure how chunks of solid metallic elements form, but from what I remember it's probably water-based geochemistry. Don't forget, though, that "kilograms of the same element" is pretty rare, and the Earth's crust is almost entirely silicates and a smattering of other molecules, with pure elements being hardly a rounding error. Ed: here's a lecture from a geologist about the geology behind a particular gold mine. I saw it a while back and don't remember the details, but I'm posting now before noprocrast kicks me out: https://youtu.be/QsBZfRJihdw https://youtu.be/QsBZfRJihdw