Serpentine

Serpentine forms when basic and ultrabasic rocks are altered. Antigorite occurs on every continent, and lizardite is the most common serpentine overall. Notable bowenite sources include Afghanistan, China (light yellowish green), New Zealand, the Transvaal in South Africa (banded green) and the eastern United States; williamsite is best known from Rock Springs, Maryland, and lizardite from the Lizard Peninsula in Cornwall, England. Rocks that mix serpentine with carbonates include verd antique and Ireland's Connemara marble.

Serpentine is often sold as a jade simulant, sometimes under misleading names such as "Korean jade"; "Styrian jade" is also a serpentine. Jadeite and nephrite have higher specific gravity and refractive index and are far tougher, so gemologists can usually tell them apart easily. Serpentine may be resin-impregnated for stability or dyed, either green to look more like jade or in colors outside its natural range such as orange and purple. Its low hardness means it scratches easily.

All serpentines are soft enough to be scratched by household dust, so they suit earrings, pendants and brooches better than rings, which need protective settings. Do not use steam or ultrasonic cleaners; clean only with a soft brush, mild detergent and warm water. Chrysotile is asbestos: finished, non-fibrous pieces are safe to wear, but cutting it releases hazardous dust.

Serpentine has long been carved: the Taíno of the Caribbean made zemí figures, objects that housed an ancestral spirit, from serpentine rock, and the Māori carved heirloom hei-tiki pendants from a clear form of bowenite known as tangiwai pounamu. Bowenite is named after G. T. Bowen, who studied Rhode Island material but misidentified it as nephrite. Serpentine is the state rock of California, and bowenite is the state mineral of Rhode Island.