OC Richard, I'm wondering if the reason for the lack of documented rationale for buying fur sporrans, especially for magical or ritualistic reasons, is that no such rationale existed. Written history or rationale might be missing, but context would provide clues if such powers were thought to be associated with the fur sporran.

I tend to believe that availability of materials -- small critters, horses, sheep, etc. -- probably had a lot to do with the choice. Daniel Boone likely didn't have any particular divine reason to have his coonskin cap. I have little experience with processing hides, but does keeping the fur make it easier/faster for the leather-maker to have material with which to work? Scraping off all that hair takes time.

For that matter, are there indications that sporrans were made of anything but leather? Did people from the early days of kilts make sporrans out of tartan cloth? How about other parts of the animal, such as bones?