We extract aluminum only from bauxite because it's slightly (think 5%) less expensive to refine it from bauxite than the next class of materials.
If all of world's bauxite reserves ran dry, we would move to the next best sources, and this would impact aluminum prices less than typical yearly variations in electricity costs near smelters.
Nearly all aluminum minerals are potential ores for aluminum, the only question is how much other, undesirable material (mostly silica) you need to remove. Bauxite is nice because nature did a lot of the early separation process steps (slightly acidic rains washed away silica over millennia).
Lithium isn't found as a pure element, if that's what you mean. It's part of minerals bound up into stable molecules. So it won't blow up.
It's very hard to find anything volatile in nature, pretty much by definition. Exceptions are things that are continually generated, eg you can find reactive oxygen in nature because plants keep making more. That or things that are only volatile once you purify or transform them in some way.
We just weren't looking very hard to find lithium compared to lead till very recently.
https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...