Gem library
Malachite
Copper green, in concentric ribbons
Malachite is a copper carbonate, the most recognisable green mineral in the world thanks to its concentric ribbons. It is also a prospecting marker: where malachite outcrops, copper lies beneath — a rule applied since the Neolithic.
- Hardness (Mohs)
- 3.5 – 4
- Density
- 3.6 – 4.05
- Crystal system
- Monoclinic
- Refractive index
- 1.655 – 1.909
- Cleavage
- Perfect on {201}, barely visible in masses
Mineralogical identity
- Family
- Carbonates — malachite group
- Species
- Malachite
- Chemical formula
- Cu₂CO₃(OH)₂
- Crystal system
- Monoclinic
- Classification
- Collector's mineral · ornamental stone
- Rarity
- Common
- Indicative price
- €0.50 – 10/ct
Etymology
From the Greek malakhe, the mallow, whose leaves are a similar green — or from malakos, «soft», for its low hardness.
Physical & optical properties
- Hardness (Mohs)
- 3.5 – 4
- Density
- 3.6 – 4.05
- Refractive index
- 1.655 – 1.909
- Birefringence
- 0.254 (very strong)
- Cleavage
- Perfect on {201}, barely visible in masses
- Fracture
- Splintery
- Lustre
- Silky to dull, vitreous on crystals
- Diaphaneity
- Opaque
- UV fluorescence
- None
- Pleochroism
- None
- Colours
- green, deep green, light green
Formation, geology & history
Formation in the oxidation zone
Malachite forms where water and oxygen attack deep copper ores: chalcopyrite, bornite, cuprite. The released copper recombines with dissolved carbon dioxide to precipitate as botryoidal crusts, stalactites and zoned masses. Each band records a change in concentration, producing the alternations of light and near-black green that make its beauty. It almost always keeps company with azurite, bluer and less stable: azurite spontaneously converts to malachite in the presence of moisture, a phenomenon visible on many old specimens and on medieval frescoes whose blue skies have turned green.
The tsars' stone
The Ural deposits, discovered in the eighteenth century, yielded blocks of several dozen tonnes. Imperial Russian workshops developed the «Russian mosaic» technique: thin plates of malachite glued to a stone or metal support and arranged to give the illusion of a solid block. The result can be seen in the Winter Palace in Saint Petersburg, whose Malachite Room includes columns, fireplaces and whole vases. Those deposits are now practically exhausted, and Congolese Katanga has taken over the world market.
A pigment and a poison
Ground, malachite yields mountain green, a pigment used in Egyptian, Byzantine and medieval painting. The Egyptians also made eyeshadow from it. A caution nonetheless: malachite contains about 57 % copper, and its dust is toxic by ingestion and inhalation. Cutting and polishing must be done wet, with respiratory protection. The polished, handled stone is not dangerous, but do not leave it in a water jug or put it in your mouth.
How to recognise it
- Concentric bandingGreen bands in circles, eyes and festoons are the malachite signature. A plain green with no pattern is suspect.
- Low hardnessIt is easily scratched by a steel needle and even by a copper coin. A banded green stone that scratches glass is dyed agate or glass.
- High density3.6 to 4: heavy in the hand for its volume, a clear sense of density that resin imitations do not reproduce.
Imitations, treatments & confusions
- Resin and reconstituted powderVery widespread: malachite powder or pigment set in resin. Over-regular patterns, often identical from bead to bead, abnormal lightness, plastic smell on the hot point.
- Green-dyed howlite or magnesiteSimilar hardness but no density: the piece feels light. The dye concentrates in the veins and bleeds onto damp cotton.
- Marbled green glassBubbles, mould seams, immediate warmth, swirled rather than concentric patterns.
Deposits & origins
Democratic Republic of Congo (Katanga — the finest, in contrasting ribbons), Zambia, Namibia, Russia (Urals: historic deposits now exhausted), Australia, Morocco, Arizona (USA), Mexico
Care & precautions
- Never prolonged water: malachite is sensitive to moisture and acids, including acidic sweat and vinegar.
- Clean with a barely damp soft cloth and dry at once. No household products, no ammonia.
- Ultrasonic cleaners and steam are absolutely forbidden: it disintegrates.
- Never cut or sand it dry: copper dust is toxic. Always work under water.
Traditions & crystal healing
- Chakras
- Heart
- Zodiac signs
- Libra · Scorpio · Capricorn
- Element
- Earth
A heart stone in tradition, but reputed powerful and direct: it is presented as a stone that «brings out» buried emotions rather than soothing them. The Egyptians wore it as a protective amulet and as eye paint; in traditional use it is rarely recommended to beginners.
The virtues described here belong to tradition and cultural heritage. They are in no way medical advice and never replace a consultation.
Frequently asked questions
Is malachite toxic?
Polished and handled, no. Its dust is: it contains 57 % copper. Never cut it dry, do not leave it in drinking water, do not put it in your mouth.
Is my malachite reconstituted?
Check the weight (the real thing is heavy), the regularity of the pattern (too perfect means resin) and the hardness. True malachite is scratched by a needle; resin is scratched by a fingernail.
Can it go in water?
No. Water, and especially soapy or acidic water, attacks the copper carbonate and dulls the polish. A barely damp cloth is enough.