Just a small theory of mines

According to Lithnilian, the Ayleids were able to grow and cultivate Welkynd stones. I think that actually, many gem geodes encountered on Nirn are living beings endowed with a (very slow) metabolism. The albino spiders seen in Solstheim are a species of pollinators for such stones. Albino spiders live in mutualism with gems : spiders allow the gems to reproduce and gems endow spiders with a magical power that enhances their survival odds.

There actually are spiders associated to the garnet and diamond; the reason it doesn't appear in-game is that Servos Rendas' imbuing chamber needs to be perfected.

The gigantic glowing mushrooms in Blackreach are pollinators for Aetherium. I wouldn't be astonished if there existed somewhere a den of Aetherial spiders awaiting to be discovered.

The albino spiders might actually be what inspired the Dwemer into creating their spider robots, in an attemps to optimize and automatize the culture of the minerals they need for their arts and crafts, and architecture. The ores and gems carried by the working spiders might actually be cuttings that would be resited and planted in fertile stone in order to propagate the living minerals. If we assume this, then the mechanic city of Fahlbtharz, which cointains oil spiders, might actually be the place where Dwemeri spiders were invented.

I think that these living, growing minerals might actually be descendants of the sacrificed Ehlnofey, the well-named Earth Bones. Like their et'Ada ancestors, I suspect that every gem has a proper inner-realm - see the pocket realm which is internal to Azura's Star. The Soul Cairn might actually be the symbiotic amalgamation of the inner-realms of countless black soulgems, in which case the cristalline nature of the Ideal Masters would be a litlle less mysterious.

The magic which imbues altered albino spiders does not originate from Magnus. They originate directly from the stones, the Earth Bones, who also were et'Adas. It would be interesting to study the difference between the mineral magic and the solar one.

Stahlrim is one of the fastest growing ores : it grows fast enough to be used as a way to embalm corpses. The reason why Ancarion is on Solstheim is thus not his desire for powerful weapons -- I have no doubt that the Altmer can and do forge very good weapons. The reason of his willingness to buy stahlrim gear is that the Thalmor wants to use them as cuttings to implant them in Alinor. Indeed, the fast growth of Stahlrim can be seen as a clue that Stahlrim sources are Ehlnofey who are less deeply asleep than others. The Thalmor hopes it would more easily awaken the sentience of that specific ore, "resurrect" the et'Ada it once was. Awakening the sacrificed Ehlnofey would lead them closer to restoring the Dawn Era.