metamorphic
Serpentine-rich greenstone
Serpentinite, commonly dominated by serpentine-group minerals (antigorite, lizardite, chrysotile)
AI-generated identification · may be incorrectGreen to yellow-green, mottled and dull-to-waxy, with irregular fracture and no obvious crystal faces; hardness about 2.5–4 Mohs and specific gravity roughly 2.5–2.6. The pale patches may be weathered serpentine, carbonate, or another alteration mineral.
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Physical properties
Green to yellow-green, mottled and dull-to-waxy, with irregular fracture and no obvious crystal faces; hardness about 2.5–4 Mohs and specific gravity roughly 2.5–2.6. The pale patches may be weathered serpentine, carbonate, or another alteration mineral.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite react with water during hydrothermal alteration, commonly in ophiolites and subduction zones. Serpentinite can form from Precambrian to modern tectonic settings; age cannot be determined from the photograph.
Uses & applications
Used as decorative stone, carvings, cabochons, and occasionally aggregate or building stone, though chrysotile-bearing material requires care because of asbestos fibers.
Geological facts
Its green color reflects iron-bearing serpentine and associated magnetite. Some specimens are weakly magnetic and may contain chromite, talc, or carbonate veins.
Field identification & locations
Look for a soft, waxy green surface, mottling, slickensides, and white or pale veins; it commonly occurs in tectonic belts and ophiolites. A hardness test and asbestos-aware laboratory examination are needed for reliable identification.
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