Grave Dust

Grave Dust is a reagent used by the magic school of Necromancy in Ultima Online.

Ultima Online
Grave dust is exactly what the name says, dust collected from graves. Despite being easy to gather (apart from the threat of udead) and being plentiful, it does have some serious power behind itself, powering spells of great power in this school of magic.

Trivia

 * Besides its use in Necromancy, it also is used in the skill Alchemy as a reagent.