lithic

adj: a color darker than black, derived from lithium

Usually associated with bipolar disorder or mania. People prescribed with BPD sometimes think of moods as colors. Lithic is darker than black.

Can sometimes be used to actually describe something dark, but is usually associated with BPD emotions.

"I'm so depressed, I'm lithic."

"He's near suicidal; he's lithic."

"His eyes were so dark they seemed lithic."