Azura's Star is the reward for completing the Azura quest, it is a reusable soul gem useful for Mages with enchantments on their staffs and swords.
It is possible to trap all the souls of creatures in; however it cannot store NPCs souls in. Also, it cannot be turned into a black soul gem. In effect it is a reusable Grand Soul Gem and can help clear space in your inventory as you won't need that many more Soul Gems, if any at all.
Related ThreadsAzura star = bull@#$%! - last post @ Sep 10, 2012
Azura star replacements? - last post by @ Feb 23, 2004
Azura Star Glitch? - last post by @ Jul 23, 2010
azuras star - last post by @ Jun 5, 2005
Star of Azura - last post by @ Oct 28, 2004