metamorphic
Greenstone
Metabasalt / Chlorite-actinolite-epidote schist
Hardness: 5-6 on Mohs scale, Color: Various shades of green (dark green, grayish-green, olive), Luster: Dull to vitreous, Crystal structure: Microcrystalline to fine-grained, Specific Gravity: 2.7-3.0
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Physical properties
Hardness: 5-6 on Mohs scale, Color: Various shades of green (dark green, grayish-green, olive), Luster: Dull to vitreous, Crystal structure: Microcrystalline to fine-grained, Specific Gravity: 2.7-3.0
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks such as basalt, gabbro, or diabase, typically in oceanic crust or subduction zone environments.
Uses & applications
Used historically for stone axes and ornaments, in modern landscaping, decorative stone, and by lapidaries for cabochons and carvings.
Geological facts
Greenstone gets its characteristic color from green minerals like chlorite, epidote, and actinolite that form during the metamorphic alteration of original minerals like pyroxene and plagioclase.
Field identification & locations
Found worldwide in ancient greenstone belts and areas with historical tectonic activity. Easily identified by its distinct greenish hue and smooth, weathered appearance in riverbeds or beaches.
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