It's something that will be used during the last quest for the Mage's Guild.
Spoiler - the Archmage will sacrifice himself to put his soul into the gem, and then this will protect you from the magic of Mannimarco (the head Necromancer) so you can kill him.
In Skyrim, the Black Star is a reusable, black soul gem that can hold both black and white souls. It is obtained by completing the quest "The Black Star." Black soul gems can hold the souls of humanoid beings, while white soul gems can only hold the souls of animals and monsters.
GET soul gem and unlock the soul gems upgrade
you find sunburns soul gem in his adventure packs level
Basically, Any sentient human being or dremora soul can be placed inside the gems, and will automatically equal to a Grand soul (highest level soul in the game)
Darklight krypt is where you find sunburns soul gem
if they have a soul in them, then get into the arcane university and use an altar of enchanting to put enchantments on your normal weapons, or equip them in the inventory to recharge weapons that already have an enchantment. if they have no souls in them, you can cast a soul trap spell on a creature (only black soul gems can contain humans) and kill the thing you casted the spell on while it's still in effect. if you do that, you will trap the soul in the gem. now go and enchant. oh, and you can enchant armour and clothes, too.
Sorry I don't know but I know where Sunburns soul gem is it is in Dragon's Peak about 5 minutes into it lean of the island and there is a dragon waiting there to take u to his soul gem
Whirlwind's soul gem is on Chapter 17, Creepy Citadel. After the little goblin puzzle, there is a platform with two Gargantulas. Defeat them to open the gate and get the soul gem. Hope this helped.
In Skyrim you can either take them from a person you have killed or more commonly they are found as random loot, usually in caves where a lot of necromancers live. They can also be crafted with the lightning attractor in the Soul Cairn (Dawnguard DLC), can be found from geode veins in Blackreach and can be purchased from Enthir in Winterhold and Falion in Morthal.
Black Soul Gems are the only soul gems that can trap the soul of an NPC, including all ten playable races, and NPC daedra such as Dremora, and Shivering Isles' Aureals and Mazken.
you find the soul gem in darkwater cove but i dont know the exact place in the level
its on oilspill island