Why do minerals often show up as streaks buried under the ground?
The question came to mind because I saw it mentioned somewhere that gold is created naturally only in supernova blasts. I don’t know if that’s true or not (by the way, is it?) but it got me wondering how all the gold ends up congregating together in big chunks and streaks you can find if you dig deep enough. Why the chunks? Why isn’t it simply randomly dissolved (so to speak) throughout the earth?
I think I might know the answer, actually, but I wanted to ask because I’m not sure. My guess is it’s because minerals with different densities tend to fall into layers when they’re all melted together, and then as they solidify, they form these “streaks” I’m talking about.
Actually, now that I typed it out, I’m pretty sure that’s right.
But what the heck, I’ll post this question anyway.
It’s not because they form layers when they are “melted together,” but rather that they crystallize out of solution under different conditions.
Rocks when formed are often not solid, but have cracks or other kinds of channels in them. These can become filled with hot water from volcanic activity in which there are all sorts of dissolved materials, which precipitate out at different temperatures. The ores formed depend on the composition of the fluid and the conditions of cooling.