Chemical composition -- Hydrated magnesium silicate. Serpentine is actually a group of three minerals having the same chemical composition but varying physical and optical properties: bowenite (antigorite), lizardite, and chrysotile (asbestos).
Color -- White, yellow, green, brown.
Optics -- R.I. 1.53-1.57.
Durability -- Hardness 2.5, except for bowenite, 4-6.
Crystal structure -- Monoclinic (massive and fibrous -- never found in crystals).
Specific Gravity-- 2.44-2.62.
Sources -- England, China, the U.S., New Zealand.
Serpentine is mostly used in carvings as a substitute for nephrite jade, for which it is sometimes mistaken.