metamorphic
Greenstone pebble (likely serpentinite or altered basalt)
Serpentinite, predominantly serpentine-group minerals; exact identification requires testing
AI-generated identification · may be incorrectOlive-green, fine-grained, matte to slightly waxy surface with faint veining and rounded water-worn form. Typical hardness is about 2.5–4 Mohs for serpentinite (basalt is about 6); no visible cleavage; specific gravity commonly 2.5–2.7.
Identified More metamorphic →
Explore Greenstone pebble (likely serpentinite or altered basalt) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Olive-green, fine-grained, matte to slightly waxy surface with faint veining and rounded water-worn form. Typical hardness is about 2.5–4 Mohs for serpentinite (basalt is about 6); no visible cleavage; specific gravity commonly 2.5–2.7.
Formation & geological history
Likely formed by hydrothermal alteration of ultramafic rock at a convergent plate margin, or possibly represents a weathered green basalt. Serpentinite can form from Precambrian to modern tectonic settings.
Uses & applications
Used as a decorative stone, carving material, and occasionally aggregate; attractive pieces may be polished for jewelry or lapidary work. This small pebble has minimal commercial value.
Geological facts
“Greenstone” is a field term, not a single rock species. The green color commonly comes from serpentine, chlorite, epidote, or altered iron-bearing minerals.
Field identification & locations
Check hardness, streak, magnetism, and density; serpentinite is usually softer and waxier than basalt and may show fibrous or slick surfaces. Common in ophiolites and tectonic belts worldwide, including California, New Zealand, Italy, and the Appalachians.
More like this
