What erythrite is
Erythrite is a hydrated cobalt arsenate. It forms when cobalt arsenide ores such as skutterudite and cobaltite weather, and usually appears as a pink crust, the cobalt bloom that prospectors once used as a sign of cobalt below. It was described in 1832 and named from the Greek erythros, red. When the species was re-examined, the International Mineralogical Association moved its type locality to Bou Azzer, where specimens are far more plentiful.
It forms a complete series with annabergite, its green nickel equivalent. Distinct crystals, blades and radiating sprays, are rare; most erythrite is crust or tiny aggregates. That rarity is what gives good crystal specimens their value.
Bou Azzer, the source of fine erythrite
Bou Azzer, in the Anti-Atlas of southern Morocco, is a cobalt-arsenic district and, since the IMA revision, the type locality of erythrite. It is one of the world's notable erythrite localities, alongside Schneeberg in Germany and Cobalt, Ontario, and today it supplies most of the erythrite crystal specimens sold to collectors. Bou Azzer pieces often show deep magenta blades on quartz or on dark cobalt ore.
What erythrite costs: price data from October 2026
Erythrite is far more expensive than the lead minerals on this site. FossilEra, a large online dealer, had none in stock on 28 October 2026.
| Source | Listings | Price |
|---|---|---|
| eBay, Bou Azzer erythrite, fixed price | 233 | Median $85, middle half $26 to $365 |
| eBay, highest listing | $1,800 | |
| FossilEra | 0 | None in stock |
How to judge an erythrite specimen
With erythrite the crystals are everything:
- Distinct, long, transparent blades or full sprays, rather than crust.
- Deep magenta to crimson colour.
- Undamaged blades: at 1.5 to 2.5 on the Mohs scale, they bend and break at a touch.
- Contrast with white quartz or dark matrix.
Is erythrite safe? Handling and care
Erythrite is about 25% arsenic by weight. Handling and displaying it is safe if you wash your hands afterwards. Never lick it, ingest it, use it in water or elixirs, or cut and grind it. Keep it away from children and pets, ideally in a closed case.
It holds eight molecules of water in its structure; heat drives that water off and spoils the crystals. Keep it away from heat and strong sunlight, never wash or ultrasonically clean it, and remove dust only with a gentle blower.
Questions collectors ask
Is erythrite safe?
It contains about 25% arsenic. It is safe to handle and display if you wash your hands afterwards and never ingest it, cut it or use it in drinks or elixirs.
How do you pronounce erythrite?
ERR-uh-thrite (Merriam-Webster: ˈer-ə-ˌthrīt), from the Greek erythros, red.
What is erythrite used for?
Historically it was a guide to cobalt ore. Today its value is as a collector's mineral.
How much is erythrite worth?
On 28 October 2026, fixed-price eBay listings for Bou Azzer erythrite had a median asking price of $85, with the middle half between $26 and $365.