Judging quality
Unmistakable purple-crimson color with a silky lustre. Very soft and easily crushed; sprays are hollow and fragile.
Arsenate
Erythrite
Cobalt bloom — brilliant magenta needles and crusts that form where cobalt ores weather. Moroccan Bou Azzer specimens with radiating crimson sprays are the classic.
Care
Arsenic-bearing; wash hands after handling and never wet-clean. Dust with a puffer only.
History & lore
Miners used the pink bloom as a field indicator that cobalt and silver ore lay beneath — the German Kobold, goblin, gave cobalt its name.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Erythrite
- What is Erythrite?
- Cobalt bloom — brilliant magenta needles and crusts that form where cobalt ores weather. Moroccan Bou Azzer specimens with radiating crimson sprays are the classic.
- How hard is Erythrite and what is it made of?
- Erythrite is a Arsenate-family mineral with the composition Co3(AsO4)2·8H2O. It crystallizes in the monoclinic system and rates 1.5-2.5 on the Mohs hardness scale. It occurs in magenta, pink-red, purple.
- Where does Erythrite come from?
- Notable localities for Erythrite include Bou Azzer, Morocco, Germany (Schneeberg), Ontario, Canada.
- How do you tell good Erythrite from filler?
- Unmistakable purple-crimson color with a silky lustre. Very soft and easily crushed; sprays are hollow and fragile.
- How do you care for Erythrite?
- Arsenic-bearing; wash hands after handling and never wet-clean. Dust with a puffer only.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.