metamorphic
Greenstone
Metabasalt (composed of chlorite, epidote, and actinolite)
Hardness: 5-7 (Mohs scale), Color: Dark green to grayish-green with rusty iron oxidation, Luster: Dull to waxy, Crystal Structure: Microcrystalline with massive texture, Cleavage: None/Irregular fracture, Specific Gravity: 2.7-3.3
Identified More metamorphic →
Explore Greenstone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-7 (Mohs scale), Color: Dark green to grayish-green with rusty iron oxidation, Luster: Dull to waxy, Crystal Structure: Microcrystalline with massive texture, Cleavage: None/Irregular fracture, Specific Gravity: 2.7-3.3
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) at low temperatures and high pressures, typically in subduction zones or orogenic belts.
Uses & applications
Used primarily as rough construction aggregate, road base, and occasionally in lapidary for carvings or as ornamental stone if high quality.
Geological facts
The green color is derived from chlorite, epidote, or actinolite minerals replacing the original pyroxene and plagioclase in the parent rock. Many greenstones are part of ancient 'Greenstone Belts' representing some of Earth's oldest crustal fragments.
Field identification & locations
Identify by its characteristic dull green hue and toughness. Often found in mountain ranges or ancient continental shields. Field identification involves looking for iron-stained weathered surfaces and metamorphic textures.
More like this
