Black Vitriol is a rare mineral only used for one recipe in the game.
It is not technically considered a gem and cannot be placed within a gem bag.
Sources
Black Vitriols are found in Dark Iron Deposits, Mithril Deposits, Ooze Covered Mithril Deposits, Ooze Covered Thorium Veins, and Small Thorium Veins.
Black Vitriol as an ingredient
Patch changes
- Patch 6.0.2 (2014-10-14): Stacks to 200, up from 20.