Serpentine
Serpentine
Hydrous magnesium silicate group used as ornamental stone and jade simulant
Serpentine is a group of hydrous magnesium silicate minerals — principally antigorite, lizardite, and chrysotile — typically green to yellow-green and translucent to opaque, used as ornamental stone, in carvings, in cabochon jewellery, and historically as a jade simulant. The serpentine group occurs widely worldwide as the principal alteration product of olivine in ultramafic rocks, with major commercial sources in China, Italy, Afghanistan, New Zealand, Canada, and the United States. Serpentine is materially softer and less tough than nephrite jade, with which it is regularly confused in trade and consumer contexts, and the distinction between the two materials is one of the more practically important identification questions in coloured-stone retail.
Mineralogy
The serpentine group has the simplified formula Mg3Si2O5(OH)4, with iron substitution for magnesium accounting for the green colouration of most ornamental varieties. The three principal polymorphs — antigorite (platy), lizardite (massive fine-grained), and chrysotile (fibrous) — differ in crystal structure and habit but share the basic chemistry. Most ornamental serpentine traded for cabochon and carving use is antigorite or fine-grained lizardite, which polish to a smooth, slightly waxy lustre. Chrysotile, the fibrous variety, is the form historically mined as commercial asbestos and is no longer in commercial use.
Mohs hardness is 3 to 6, varying considerably across the group and with the fineness of the mineral aggregate. Antigorite at the harder end approaches 5.5 to 6 in fine-grained massive form, comparable to opal but materially softer than nephrite jade (6 to 6.5 with exceptional toughness from interlocked fibrous structure). Specific gravity is around 2.5 to 2.6.
Sources and varieties
The principal commercial varieties of ornamental serpentine include bowenite (a hard, fine-grained green serpentine from Rhode Island, USA, and from China, often sold as new jade or Suzhou jade), williamsite (a translucent apple-green serpentine from Pennsylvania), and verd antique (a marble-and-serpentine ornamental rock used in architecture and decorative objects rather than jewellery). Major commercial sources include the Liaoning Province of China, the Xinjiang and Qinghai regions for higher-quality material, the South Island of New Zealand for tangiwai (a translucent serpentine traded under Maori naming conventions), and the Shilu and Susa workings in Afghanistan.
Confusion with jade
The most commercially important issue with serpentine is its widespread sale, intentional or otherwise, as jade. Translucent green serpentine — particularly Chinese bowenite — bears a strong superficial resemblance to nephrite and to lower-quality jadeite, and the two materials have been confused in trade contexts since the nineteenth century. The distinction is material: nephrite has the toughness that has made it the principal carving stone of east-Asian and Maori cultures over millennia, while serpentine is materially softer and less tough, more readily scratched, and less suitable for carving applications that require structural durability. Jade-trade dealers and laboratories test routinely for the distinction; refractive index (1.55–1.57 for serpentine, 1.61 for nephrite, 1.66 for jadeite) and specific gravity provide quick discrimination.
Use in jewellery and ornament
Serpentine is cut and polished as cabochons, beads, and small carvings, and worked at larger scale into ornamental objects, decorative panels, and architectural inlay. Ring use is generally inadvisable for the softer serpentine varieties — the hardness is below the practical threshold for daily-wear ring centres — though the harder bowenite at Mohs 5.5–6 can be used in protected ring settings with care. Pendant, earring, and brooch applications are unproblematic. The waxy-to-greasy lustre and the often-translucent green body provide a workable aesthetic in the visual register of jade without the price.
In the trade
Honest trade in serpentine treats it as serpentine, named explicitly, and prices it accordingly — materially below jade. Trade names such as new jade, Korean jade, Soochow jade, and others have been used historically for serpentine, and consumer-protection considerations in jurisdictions that regulate gemstone naming require accurate disclosure. For dealers and retailers, the practical discipline is straightforward: identify and label serpentine accurately, do not represent it as jade, and price it at the level appropriate to its material qualities. The customer who wants jade should be sold jade; the customer who wants the look of jade at a serpentine price point should know what they are buying.