Gem library
Serpentine
The snakeskin of the oceanic mantle
Serpentine is not a mineral but a group, produced by hydrothermal transformation of oceanic mantle rock. It is also jade's chief imitator — sold worldwide under the misleading name «new jade».
- Hardness (Mohs)
- 3 – 5 (bowenite: up to 6)
- Density
- 2.44 – 2.62
- Crystal system
- Monoclinic · orthorhombic depending on species
- Refractive index
- 1.555 – 1.575
- Cleavage
- Perfect on {001} in some species
Mineralogical identity
- Family
- Silicates — phyllosilicates, serpentine group
- Species
- Antigorite, lizardite, chrysotile
- Variety
- Bowenite, verd antique, «new jade»
- Chemical formula
- Mg₃Si₂O₅(OH)₄
- Crystal system
- Monoclinic · orthorhombic depending on species
- Classification
- Ornamental stone (rock)
- Rarity
- Very common
- Indicative price
- €0.10 – 2/ct
Etymology
From the Latin serpens, the snake: the mottled, scaly look of some varieties evokes reptile skin.
Physical & optical properties
- Hardness (Mohs)
- 3 – 5 (bowenite: up to 6)
- Density
- 2.44 – 2.62
- Refractive index
- 1.555 – 1.575
- Birefringence
- 0.004 – 0.014
- Cleavage
- Perfect on {001} in some species
- Fracture
- Splintery to conchoidal
- Lustre
- Greasy to waxy, silky if fibrous
- Diaphaneity
- Translucent to opaque
- UV fluorescence
- None
- Pleochroism
- None
- Colours
- green, olive green, yellow green, brown
Formation, geology & history
Born of water and mantle
Serpentinisation is a major Earth process: when seawater penetrates oceanic mantle peridotites along the ridges, olivine and pyroxene convert to serpentine, releasing hydrogen and methane. The reaction swells the rock by 40 %, gives off heat, and feeds unique chemosynthetic ecosystems such as the Lost City hydrothermal field. These serpentinised rocks, or serpentinites, outcrop in ophiolite massifs — fragments of oceanic crust carried onto continents by tectonics, visible in the Alps, in Cyprus and in New Caledonia. Three main minerals make up the group: antigorite, lizardite and chrysotile.
Chrysotile and asbestos
Chrysotile, the fibrous form of serpentine, is white asbestos — 95 % of all asbestos used industrially, banned in the European Union since 2005. Its fibres, inhaled, cause asbestosis and mesothelioma. That imposes a clear precaution: massive ornamental serpentine (antigorite, bowenite) presents no risk in handling, but it must never be sawn, sanded or polished dry, because some deposits contain chrysotile veins. Lapidaries always work under water with extraction. A serpentine with a fibrous, silky look deserves particular caution.
Fake jade and real qualities
Its green colour, greasy lustre and fine grain make serpentine the universal jade substitute: «new jade», «Korean jade», «Suzhou jade», «olive jade» all denote serpentine. It differs by its softness (3 to 5 against 6-6.5), its lightness and its dull sound. Bowenite, a hard translucent variety from Rhode Island and New Zealand, is the most estimable and was long confused with nephrite. Historically, serpentine has been much used in sculpture — Roman verd antique, Minoan vases, Egyptian statuettes — precisely because it is easy to work.
How to recognise it
- Greasy lustre and soapy feelSerpentine has an oily finish and a slightly soft, almost silky feel that distinguishes it from denser, colder jade.
- Scratched by a knifeHardness 3 to 5: a knife marks it, except on bowenite. Nephrite jade resists a knife.
- Dull soundStruck, it sounds short and muffled. Jade rings clear and long — the quickest test to separate them.
Imitations, treatments & confusions
- Sold as jadeThe most massive deceptive use in the stone trade. The names «new jade», «Korean jade» and «olive jade» all denote serpentine, ten to a hundred times cheaper than real jade.
- Dyed serpentineVery bright or apple greens are often dyed to better imitate jadeite. Colourant in cracks, deposit on cotton soaked in acetone.
- Confusion with aventurine and chrysopraseAventurine has mica flakes, chrysoprase is a quartz of hardness 7. Serpentine, being softer, is scratched by a knife.
Deposits & origins
China (main source of «new jade»), Afghanistan, Italy (Aosta Valley, verd antique of Susa), United States (California, where it is the state rock; Rhode Island for bowenite), New Zealand, Korea, Canada (Quebec, asbestos), France (Alps, Brittany)
Care & precautions
- Brief rinsing in warm soapy water and immediate drying. No soaking.
- No salt or acids; no ultrasonic cleaning on soft or fibrous pieces.
- Very soft: it is scratched by contact with other stones and loses its polish. Individual storage.
- Never sand, saw or polish dry: some deposits contain chrysotile fibres (asbestos). Working under water is mandatory.
Traditions & crystal healing
- Chakras
- Heart
- Zodiac signs
- Gemini · Taurus
- Element
- Earth
Tradition associates it with moulting and renewal — the image of the snake shedding its skin. It is credited with helping to let go and digest difficult experiences. Ancient Mediterranean cultures wore it as an amulet against venomous bites, by analogy of form.
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 «new jade» jade?
No, it is serpentine. It is softer (3-5 against 6-6.5), lighter, sounds dull when struck and is worth ten to a hundred times less than nephrite jade.
Is serpentine dangerous?
Massive and polished, no. But never saw or sand it dry: some deposits contain chrysotile, the fibrous form that constitutes white asbestos.
How do I tell it from jade?
The sound (dull against clear and sustained), the hardness (a knife scratches it), the weight (lighter) and the slightly soapy feel.