|  | 
Definition of Cobalt bloom
1. Noun. A reddish mineral consisting of hydrated cobalt arsenate in monoclinic crystalline form and used in coloring glass; usually found in veins bearing cobalt and arsenic. 
|  | 
1. Noun. A reddish mineral consisting of hydrated cobalt arsenate in monoclinic crystalline form and used in coloring glass; usually found in veins bearing cobalt and arsenic.