metamorphic
Polished greenstone (likely serpentine or nephrite-like material)
Serpentine-group minerals, commonly antigorite/lizardite; possible nephrite (actinolite–tremolite amphibole)
AI-generated identification · may be incorrectDark olive-green, mottled and weakly translucent with a waxy to dull luster; likely Mohs 3–6, with no obvious cleavage and a fine-grained compact texture. The rounded, polished surface makes exact identification uncertain.
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Physical properties
Dark olive-green, mottled and weakly translucent with a waxy to dull luster; likely Mohs 3–6, with no obvious cleavage and a fine-grained compact texture. The rounded, polished surface makes exact identification uncertain.
Formation & geological history
Serpentine forms when ultramafic mantle rocks undergo hydration and alteration, commonly during oceanic or tectonic processes; nephrite forms by metamorphic alteration involving magnesium-rich rocks. Ages vary widely by locality, from Precambrian to recent tectonic settings.
Uses & applications
Used for carvings, cabochons, beads, ornamental objects, and occasionally architectural stone; nephrite-quality material can be valuable, while ordinary serpentine is inexpensive.
Geological facts
Greenstone is a broad trade term rather than a single mineral. Serpentine is generally softer and lighter than nephrite and may show a greasy or waxy feel.
Field identification & locations
Look for mottled olive coloration, compactness, and waxy luster; hardness and specific-gravity tests, plus microscopy or Raman/XRF analysis, are needed to distinguish serpentine from nephrite. Common sources include New Zealand, China, Canada, Russia, Italy, and the United States.
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