metamorphic
Polished greenstone (likely serpentine or altered basalt)
Serpentinite, chiefly serpentine-group minerals; possible chlorite/actinolite-bearing greenstone
AI-generated identification · may be incorrectDark olive-green, mottled, and highly polished with a waxy to vitreous luster; typically Mohs 2.5–4 for serpentine (harder if basaltic). Fine-grained and massive, with no visible cleavage or distinct crystals; exact identification requires hardness, streak, and mineral tests.
Identified More metamorphic →
Explore Polished greenstone (likely serpentine or altered basalt) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark olive-green, mottled, and highly polished with a waxy to vitreous luster; typically Mohs 2.5–4 for serpentine (harder if basaltic). Fine-grained and massive, with no visible cleavage or distinct crystals; exact identification requires hardness, streak, and mineral tests.
Formation & geological history
Likely formed by low- to moderate-temperature metamorphic alteration of ultramafic rock, or by metamorphism of basalt into greenstone. Such rocks range from Precambrian to recent oceanic and subduction-zone settings.
Uses & applications
Used as a decorative stone, carving material, lapidary cabochons, and tumbled specimens; some varieties are used architecturally, though fibrous asbestos-bearing serpentinite should not be cut or powdered.
Geological facts
The glossy surface and mottled green coloration are typical of lapidary greenstone, but appearance alone cannot distinguish serpentine from polished basalt, jade-like rocks, or epidote-rich material.
Field identification & locations
Common sources include California, Vermont, New Zealand, Italy, Canada, and ophiolite belts worldwide. A steel knife may scratch softer serpentine; jade-like material resists scratching, feels dense, and commonly has a granular or fibrous texture.
More like this
