metamorphic
Tumbled dark green stone, likely serpentinite or greenstone
Serpentinite (antigorite/lizardite-rich), or chlorite–amphibole greenstone
AI-generated identification · may be incorrectDark blue-green to gray-green, rounded and polished, with waxy to subvitreous luster; typically Mohs 3–5.5, massive rather than visibly crystalline, with no obvious cleavage; exact identification requires hardness, streak, and specific-gravity tests.
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Physical properties
Dark blue-green to gray-green, rounded and polished, with waxy to subvitreous luster; typically Mohs 3–5.5, massive rather than visibly crystalline, with no obvious cleavage; exact identification requires hardness, streak, and specific-gravity tests.
Formation & geological history
Serpentinite forms when ultramafic mantle rocks alter through hydration, commonly in ancient oceanic crust and subduction zones; greenstone forms by low- to medium-grade metamorphism of basalt. Ages vary from Precambrian to modern tectonic settings.
Uses & applications
Used as a decorative or carving stone, lapidary material, and occasionally architectural stone; tumbled pieces are mainly sold as inexpensive collectibles or metaphysical stones.
Geological facts
The blue-green color commonly reflects serpentine, chlorite, amphibole, or iron-bearing minerals. A small steel scratch test and examination for fibrous texture can help distinguish serpentinite from glass or slag.
Field identification & locations
Common sources include California, Vermont, New Zealand, Italy, and many ophiolite belts; the image alone cannot separate serpentinite from other dark green stones. Avoid sanding unknown serpentinite, as some varieties may contain asbestos-form minerals.
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