metamorphic
Greenstone / serpentine-rich metamorphic rock
Likely serpentinite, composed mainly of serpentine-group minerals (antigorite, lizardite, or chrysotile), with possible magnetite and chlorite
AI-generated identification · may be incorrectGreen to olive, mottled and waxy to dull luster; typically Mohs 2.5–4, massive with no obvious crystal faces, and relatively dense (about 2.5–2.6). The rounded shape suggests tumbling or natural abrasion.
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Physical properties
Green to olive, mottled and waxy to dull luster; typically Mohs 2.5–4, massive with no obvious crystal faces, and relatively dense (about 2.5–2.6). The rounded shape suggests tumbling or natural abrasion.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite are hydrated during hydrothermal alteration, commonly along tectonic plate boundaries; ages vary from Precambrian to modern tectonic settings.
Uses & applications
Used as decorative stone, carvings, countertops, landscaping material, and lapidary specimens; attractive pieces may be sold as “serpentine jade,” though they are not true jade.
Geological facts
Serpentinite can contain magnetite and may show weak magnetic response. Fibrous chrysotile varieties can contain asbestos, so cutting or abrading unknown material should be avoided without dust control.
Field identification & locations
Identify by its green mottling, soft waxy surface, low hardness, and possible soapy feel; common in ophiolites and metamorphic belts worldwide, including California, Italy, New Zealand, and Canada.
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