metamorphic
Polished greenstone (likely serpentinite or green granite)
Probably serpentinized ultramafic rock, chiefly serpentine-group minerals; exact identification requires testing
AI-generated identification · may be incorrectFine- to medium-grained, blue-green to gray-green, with a dull-to-satin polished luster and mottled pattern. Likely Mohs 2.5–5.5 depending on serpentine, magnetite, or other minerals; no obvious crystal faces or cleavage are visible.
Identified More metamorphic →
Explore Polished greenstone (likely serpentinite or green granite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Fine- to medium-grained, blue-green to gray-green, with a dull-to-satin polished luster and mottled pattern. Likely Mohs 2.5–5.5 depending on serpentine, magnetite, or other minerals; no obvious crystal faces or cleavage are visible.
Formation & geological history
If serpentinite, it formed when oceanic mantle peridotite was hydrated during low-temperature metamorphism, commonly in ophiolite belts. The specimen is human-polished; geological age depends on its source locality and cannot be determined visually.
Uses & applications
Used as decorative facing stone, carvings, countertops, and lapidary material; attractive pieces may be sold as greenstone or serpentine. Avoid cutting unknown serpentinite because some varieties can contain chrysotile asbestos.
Geological facts
The strong cylindrical shape and smooth surface indicate a worked specimen rather than a natural outcrop fragment. Similar appearance can also result from green granite, diabase, or soapstone, so the name is provisional.
Field identification & locations
Common in serpentinite belts, including California, Italy, New Zealand, Canada, and the Appalachians. Field checks include streak, hardness, density, magnetism, and acid reaction; laboratory thin-section or Raman/XRF testing is most reliable.
More like this
