metamorphic
Greenstone
Metabasalt / Greenschist
Hardness of 5 to 6 on the Mohs scale, typically mottled green in color due to minerals like chlorite, epidote, and actinolite, dull to sub-greasy luster, dense and compact crystal structure with no distinct cleavage.
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Physical properties
Hardness of 5 to 6 on the Mohs scale, typically mottled green in color due to minerals like chlorite, epidote, and actinolite, dull to sub-greasy luster, dense and compact crystal structure with no distinct cleavage.
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks such as basalt, gabbro, or diabase, typically in oceanic crust environments or subduction zones over millions of years.
Uses & applications
Used locally as decorative stone, crushed stone for construction, and historically by indigenous peoples for making polished stone tools and weapons.
Geological facts
The distinctive green color comes from secondary minerals like chlorite and epidote that replace the original pyroxenes and plagioclase during hydrothermal alteration and metamorphism.
Field identification & locations
Easily identified in the field by its distinct greenish coloration and association with other metamorphic or volcanic rocks in riverbeds and mountainous terrain.
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