This is a simple, yet complex, question that requires a satisfying answer. Hopefully it is an absolute that does not have a million different theories surrounding it, but just a strait forward truth. I found nothing when I looked it up on the wiki so I hope that someone knows here. How is a soul gem created in the first place? Where do they come from? How come there is an abundance of soul gems all over the place? Who creates them? There are no answers in the game and there is nothing that I could find in the wiki. Anybody know? The reason I want to know is related to my other topic that I posted about Zurin Arctus for the mod that I am creating.

I believe they're naturally occurring and mined. If I remember correctly, they could be mined from Blackreach.

There was a quest in Oblivion where a guy gets you to observe some growing in a cave.