Alloys that do something useful for us often do not occur in nature. However the elements are often pushed and intermingled with each other. In that way, the alloys may still tie back to your... earth magic.
I do hope you have at least one. Poetry can be both harder and easier, in different ways. It is more playful with language, in how it follows or breaks the rules. But I would encourage you to include such a section. They are far better in their native tongues than translated.