QUOTE(Ulrich453 @ Apr 11 2006, 07:57 AM)
ok, to get the Black soul gem you have to have Done the quest "Necromancers Moon"
From the mages guild......Then steal the guys note, it has instructions for the alter outside of Dark Fissure. Disregard the praying part.... place your grand soul gem inside of the alter and cast soul gem ...I think it only works on a monday night... (there has to bea light shining on it)
Any necromancer's altar will do - there are several around (mostly mage's guild quest related). You can convert a regular soul gem as specified above (except cast "soul trap" not soul gem). Then, cast soul trap on a human and kill them within the effective time of the spell and you'll have their soul in your gem!