The one major difference between black soul gems and regular soul gems is that black soul gems can be used to capture human-type creature souls. Therefore you can capture the souls of nords, redguards, orcs, etc.

How to Make Black Soul Gems

• To create black soul gems you must visit one of the following alters located at Dark fissure, Fort Istirus, Fort Linchal, and Wendelbek.

• Then you must wait for a thing called the Shade of the Renevant. The Shade of the Renevant is a purple-ish light that shines from the sky onto the four shrines. It shines all day starting at midnight for 24 hours. However, it only happens every 8 days. If it is light outside you may not be able to see the light so it is best to go there when it is dark.

• So when the light is shining down you should place a grand soul gem onto the alter.

• Then cast soul trap onto the alter.

• Now take out  your soul gem and it should be black.

Effects

Black soul gems can be used to enchant weapons. They provide very powerful abilities to your weapons. You also do not need a Grand Soul creature to use the black soul gems.

More Help

For more information please visit oblivion black soul gem