Yep so no refinery involved there, that's true. In fact here in this discussion we're dangerously close to the fact that Nickel is being quite different thing that Cobalt is for example. It's a little unnatural but ppl got used to it in Elite.
There're commodities. Those can be loaded in your cargo hold, traded, mined, given away, saved on your carrier. That is the only thing that can be mined
for real. Gold and Cobalt are both commodities and can be mined, you can prospect a roid and see, whoah, 47% gold content. Only these go through refinery. Other commodities include, but ain't limited to, foods, industry goods, weapons, minerals and many other things that you can carry in your cargo, if you have any cargo. Commodities are often about money, you're trading them, or you keep them at hand just in case, like i have a couple of tons of
Jaques Quinentian Still stored in my carrier.
And there're materials. Those are stored in a kind of separate chest, think like you carry a chest with you. A chest is splitted in two parts, each of them is again splitted in three. Raw, Manufactured and Encoded, that's for Horizons, and Assets, Goods and Data - that's Odyssey. Nickel and Iron are materials. They can not be traded normally (like for credits, however you can squeze another nickel from a material trader offering 6 chunks of iron). You can't as well mine
specifically for, say, Nickel. Mats are still dropping as a subproduct while you mine, but that's kind of more random. So if you're after Iron, Nickel, Sulfur, which are common, chances are you just getting them along the way, but rarer raw materials will come from mining in lower quantities, and very rare may not come at all. Then planetary prospecting is the way.
Things that you find at these Degraded Emissions are often materials too (tho you may very well find a couple of containers with tea), but usually manufactured ones, which will drop as well if you kill another pirate, like focus crystals. Or encoded, from a data cache or a beacon. And Odyssey materials are tied to Ody missions and bases. Materials are often about engineering - you can upgrade your ships, or suits, or weapons in exchange of them.
Inara tables list all the mats by categories.
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