THE GEMHOOD EDITORIAL LIBRARY
Erythrite gemstone guide
Erythrite — hydrated cobalt arsenate mineral. Read about characteristic appearance, Mohs hardness, safety and care.
Gem facts · Quality considerations · Care & meaning
A study in colour and character
Every shade has a story.
Typical appearances for Erythrite. Natural stones vary, and lighting or treatment can change their appearance.
Where Erythrite is found
Bou Azzer district, Morocco; Schneeberg, Germany; and other cobalt-rich deposits
Morocco
Germany
How it forms
Secondary mineral in the oxidation zones of cobalt-, nickel- and arsenic-bearing ore deposits, often appearing as “cobalt bloom”.
These are representative geological or commercial sources, not certified provenance for an individual stone. Country of origin should be substantiated independently when relevant to value.
01 / THE GEM AT A GLANCE
What is Erythrite?
Erythrite is hydrated cobalt arsenate mineral, commonly represented by the formula Co₃(AsO₄)₂·8H₂O. Mohs hardness: 1.5–2.5. Reported colours include Magenta, crimson, pink to pale rose. Secondary mineral in the oxidation zones of cobalt-, nickel- and arsenic-bearing ore deposits, often appearing as “cobalt bloom”. Magenta to red radiating needles, earthy coatings or fine prismatic crystals; arsenate composition distinguishes from similarly coloured gem minerals.
Composition: Co₃(AsO₄)₂·8H₂O. Scientific properties apply to the mineral or gem type, not as a guarantee about an untested individual product.
Erythrite is hydrated cobalt arsenate mineral, commonly represented by the formula Co₃(AsO₄)₂·8H₂O. Mohs hardness: 1.5–2.5. Reported colours include Magenta, crimson, pink to pale rose. Secondary mineral in the oxidation zones of cobalt-, nickel- and arsenic-bearing ore deposits, often appearing as “cobalt bloom”. Magenta to red radiating needles, earthy coatings or fine prismatic crystals; arsenate composition distinguishes from similarly coloured gem minerals. Characteristic features: Magenta to red radiating needles, earthy coatings or fine prismatic crystals; arsenate composition distinguishes from similarly coloured gem minerals. Documented occurrences include Bou Azzer district, Morocco; Schneeberg, Germany; and other cobalt-rich deposits. Localities describe geological reports, not the proven origin of any individual sale item. Historically called “cobalt bloom” because magenta surface coatings may mark cobalt-bearing ore zones. Collector-only mineral; do not sell as jewellery, skin-contact accessories or healing-water material because it contains arsenate. Keep in closed display, avoid handling dust, wash hands afterward; never grind, tumble, ingest or place in water. Verify identification and safe provenance; photograph colour is not enough to distinguish arsenate species. Contains arsenic and cobalt; avoid skin abrasion, ingestion, inhalation of powder and any wellness claims. Specialist testing and chain-of-custody evidence matter for high-value or hazardous materials. Genuine mineral identification requires evidence beyond colour or the appearance of a picture. Read the complete guide before acquiring a specimen.
02 / LOOK CLOSER
Colour, appearance and quality
Characteristic features: Magenta to red radiating needles, earthy coatings or fine prismatic crystals; arsenate composition distinguishes from similarly coloured gem minerals. Documented occurrences include Bou Azzer district, Morocco; Schneeberg, Germany; and other cobalt-rich deposits. Localities describe geological reports, not the proven origin of any individual sale item.
Before you choose a stone
Compare images taken in more than one lighting condition, ask for views of the actual item and check how the cut and setting change its appearance. A gemstone type is not a standard grade: each natural specimen has its own colour, inclusions and workmanship.
THE GEMHOOD BUYER'S FIELD NOTES
How to choose Erythrite: three checks
- 01
Verify identification and safe provenance; photograph colour is not enough to distinguish arsenate species.
- 02
Keep in closed display, avoid handling dust, wash hands afterward; never grind, tumble, ingest or place in water.
Contains arsenic and cobalt; avoid skin abrasion, ingestion, inhalation of powder and any wellness claims.
Collector-only mineral; do not sell as jewellery, skin-contact accessories or healing-water material because it contains arsenate.
These notes describe typical gem material and trade practices. They do not independently grade or identify a specific item offered for sale.
03 / BUY WITH CONFIDENCE
Natural, laboratory-grown, treated or imitation?
Verify identification and safe provenance; photograph colour is not enough to distinguish arsenate species. Contains arsenic and cobalt; avoid skin abrasion, ingestion, inhalation of powder and any wellness claims. Specialist testing and chain-of-custody evidence matter for high-value or hazardous materials.
These distinctions should be clear in the listing for any particular gem. Treatments are not automatically unacceptable, but an undisclosed treatment, vague mineral identity or unsupported origin claim prevents an informed purchase. Where material identity materially affects value, an independent gemological identification report may be worth considering.
A CLOSER LOOK
Formation and mineral chemistry
Secondary mineral in the oxidation zones of cobalt-, nickel- and arsenic-bearing ore deposits, often appearing as “cobalt bloom”.
Erythrite is hydrated cobalt arsenate mineral, commonly represented by the formula Co₃(AsO₄)₂·8H₂O. Mohs hardness: 1.5–2.5. Reported colours include Magenta, crimson, pink to pale rose. Secondary mineral in the oxidation zones of cobalt-, nickel- and arsenic-bearing ore deposits, often appearing as “cobalt bloom”. Magenta to red radiating needles, earthy coatings or fine prismatic crystals; arsenate composition distinguishes from similarly coloured gem minerals.
A CLOSER LOOK
Diagnostic features and lookalikes
Magenta to red radiating needles, earthy coatings or fine prismatic crystals; arsenate composition distinguishes from similarly coloured gem minerals.
Verify identification and safe provenance; photograph colour is not enough to distinguish arsenate species.
A CLOSER LOOK
Representative origins and provenance
Bou Azzer district, Morocco; Schneeberg, Germany; and other cobalt-rich deposits
A locality reference does not prove the offered specimen originates there.
A CLOSER LOOK
Uses and jewellery suitability
Collector-only mineral; do not sell as jewellery, skin-contact accessories or healing-water material because it contains arsenate.
Contains arsenic and cobalt; avoid skin abrasion, ingestion, inhalation of powder and any wellness claims.
A CLOSER LOOK
Cleaning, handling and storage
Keep in closed display, avoid handling dust, wash hands afterward; never grind, tumble, ingest or place in water.
Historically called “cobalt bloom” because magenta surface coatings may mark cobalt-bearing ore zones.
A CLOSER LOOK
Specimen image attribution and reuse licence
Specimen image adapted from 'Erythrite-176702.jpg' by Rob Lavinsky, iRocks.com on Wikimedia Commons. Licence: CC BY-SA 3.0. Photo has been resized, converted to WebP and presented against a white background.
Original source: https://commons.wikimedia.org/wiki/File:Erythrite-176702.jpg ; licence text: https://creativecommons.org/licenses/by-sa/3.0/. The image licence applies to this derivative, not the entire GemHood website.
04 / WEAR IT WELL
Erythrite in jewellery
Collector-only mineral; do not sell as jewellery, skin-contact accessories or healing-water material because it contains arsenate.
05 / MAKE IT LAST
How to care for Erythrite
Keep in closed display, avoid handling dust, wash hands afterward; never grind, tumble, ingest or place in water.
One essential care distinction
Mohs hardness describes resistance to scratching, not resistance to breaking. Gemstones with cleavage, existing fractures, porous surfaces or fillings can need extra care regardless of their hardness number. If you do not know whether a piece has been treated, begin with the gentlest appropriate cleaning method.
06 / CULTURE & MEANING
History, heritage and symbolism
Historically called “cobalt bloom” because magenta surface coatings may mark cobalt-bearing ore zones.
Traditional meanings and spiritual associations are part of cultural storytelling. They are not evidence that a gemstone diagnoses, prevents or treats any medical condition.
GOOD QUESTIONS, CLEAR ANSWERS
Erythrite FAQs
What is Erythrite?
Erythrite is hydrated cobalt arsenate mineral, commonly represented by the formula Co₃(AsO₄)₂·8H₂O. Mohs hardness: 1.5–2.5. Reported colours include Magenta, crimson, pink to pale rose. Secondary mineral in the oxidation zones of cobalt-, nickel- and arsenic-bearing ore deposits, often appearing as “cobalt bloom”. Magenta to red radiating needles, earthy coatings or fine prismatic crystals; arsenate composition distinguishes from similarly coloured gem minerals.
What is the Mohs hardness of Erythrite?
1.5–2.5; scratch hardness does not measure toughness or safety.
Where is Erythrite found?
Bou Azzer district, Morocco; Schneeberg, Germany; and other cobalt-rich deposits. Individual provenance must be independently verified.
Is Erythrite suitable for jewellery?
Collector-only mineral; do not sell as jewellery, skin-contact accessories or healing-water material because it contains arsenate.
How should I store and clean Erythrite?
Keep in closed display, avoid handling dust, wash hands afterward; never grind, tumble, ingest or place in water.
How can I identify genuine Erythrite?
Verify identification and safe provenance; photograph colour is not enough to distinguish arsenate species.
What safety or treatment issues affect Erythrite?
Contains arsenic and cobalt; avoid skin abrasion, ingestion, inhalation of powder and any wellness claims.
A NOTE FROM THE GEMHOOD EDITORIAL DESK
How to use this guide
We explain gemstone properties, known mining regions and customary treatments to help you shop more confidently. Each gemstone can vary in quality and individual provenance, so compare the actual jewellery listing and request supporting documentation if origin, treatment or natural-versus-laboratory-grown status affects your choice.
Our gemstone library is educational and does not act as a laboratory identification certificate. Independent gemological assessment is advisable for valuable or disputed claims.
EDITORIAL REFERENCES
Research and further reading
References describe mineral species and representative occurrences, not verification of any individual item for sale.
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Compare Erythrite with similar gemstones
These stones can overlap in colour, appearance or jewellery use. The mineral identity, treatments and durability may be very different.
KEEP EXPLORING
Other gemstones to discover
Educational articles describe gemstone types and common trade practices. They are not individual gemological certificates, current price appraisals or medical advice.