metamorphic
Polished greenstone (likely serpentinite or soapstone)
Serpentinite, chiefly antigorite/lizardite; possibly talc-rich steatite
AI-generated identification · may be incorrectOpaque gray-green, fine-grained, waxy to dull luster with faint mottling and polish marks; hardness typically 2–4 Mohs (serpentinite 3–5), no visible crystals, and variable cleavage. The smooth rounded edge indicates a polished or shaped slab.
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Physical properties
Opaque gray-green, fine-grained, waxy to dull luster with faint mottling and polish marks; hardness typically 2–4 Mohs (serpentinite 3–5), no visible crystals, and variable cleavage. The smooth rounded edge indicates a polished or shaped slab.
Formation & geological history
Formed by hydration and metamorphism of ultramafic mantle rocks, commonly during ancient oceanic or mountain-building events; age depends on locality. Soapstone instead forms from strongly metamorphosed, magnesium-rich rocks.
Uses & applications
Used for carving, tiles, countertops, ornaments, and lapidary pieces; attractive grades are sold as decorative stone rather than high-value gemstones.
Geological facts
Greenstone is a broad trade term, so visual inspection cannot reliably distinguish serpentinite from soapstone. Serpentinite may contain fibrous chrysotile, making cutting dust hazardous.
Field identification & locations
Common in serpentinite belts worldwide, including California, Italy, New Zealand, Canada, and parts of Scandinavia. Confirm with hardness, streak, specific gravity, acid reaction, and laboratory or XRD testing.
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