Judging quality
Deep indigo with a submetallic sheen and extreme softness — it marks with a fingernail. Bornite is more bronze and harder.
Sulfide
Covellite
Indigo copper sulfide with a peacock iridescence of purple, blue and bronze across its metallic plates. Butte, Montana produced crystallised specimens that have never been matched.
Care
Very soft and easily tarnished further. Handle by matrix, keep dry and dark.
History & lore
Named for Niccolò Covelli, who found it on Vesuvius in 1827.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Covellite
- What is Covellite?
- Indigo copper sulfide with a peacock iridescence of purple, blue and bronze across its metallic plates. Butte, Montana produced crystallised specimens that have never been matched.
- How hard is Covellite and what is it made of?
- Covellite is a Sulfide-family mineral with the composition CuS. It crystallizes in the hexagonal system and rates 1.5-2 on the Mohs hardness scale. It occurs in deep blue, iridescent, purple.
- Where does Covellite come from?
- Notable localities for Covellite include Butte, Montana, USA, Sardinia, Italy, Serbia (Bor), Peru.
- How do you tell good Covellite from filler?
- Deep indigo with a submetallic sheen and extreme softness — it marks with a fingernail. Bornite is more bronze and harder.
- How do you care for Covellite?
- Very soft and easily tarnished further. Handle by matrix, keep dry and dark.
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.