metamorphic
Greenstone
Metabasalt
Hardness of 5 to 6 on the Mohs scale, grayish-green to dark green color due to chlorite, epidote, and actinolite, dull to sub-vitreous luster, massive or fine-grained crystal structure, uneven fracture, specific gravity around 2.8 to 3.0
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Physical properties
Hardness of 5 to 6 on the Mohs scale, grayish-green to dark green color due to chlorite, epidote, and actinolite, dull to sub-vitreous luster, massive or fine-grained crystal structure, uneven fracture, specific gravity around 2.8 to 3.0
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks such as basalt, gabbro, or diabase, typically in ancient oceanic crust settings during various geological eras from Precambrian to Phanerozoic
Uses & applications
Used locally as decorative stone, crushed stone for construction, and historically by indigenous peoples for making ground stone tools like celts and adzes
Geological facts
Greenstone belts are ancient sequences of volcanic and sedimentary rocks found in cratons that often host significant deposits of gold and other metallic ores
Field identification & locations
Identified by its characteristic dull greenish hue and weathering patterns; commonly found in glacial till, riverbeds, and mountainous regions worldwide with ancient metamorphic terranes
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