metamorphic
Greenstone / Greenschist
Greenschist (metamorphosed mafic rock)
Hardness: 3.5-5 (Mohs scale), Color: dull green to grey-green, Luster: dull to silky, Structure: fine-grained, often showing faint foliation or scaly texture. Specific Gravity: 2.8-3.0.
- Hardness
- 3
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Physical properties
Hardness: 3.5-5 (Mohs scale), Color: dull green to grey-green, Luster: dull to silky, Structure: fine-grained, often showing faint foliation or scaly texture. Specific Gravity: 2.8-3.0.
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) at relatively low temperatures and pressures, typically in subduction zones or orogenic belts. Rich in chlorite, epidote, and actinolite.
Uses & applications
Traditionally used for carving stone tools (celts) by ancient cultures; currently used as construction aggregate, decorative garden stones, and occasionally for lapidary work.
Geological facts
Many of the 'greenstones' found on beaches in the Pacific Northwest or New Zealand are ancient seafloor basalts that have undergone massive pressure and chemical changes over millions of years.
Field identification & locations
Identify by its characteristic 'sage' or 'olive' green hue and relatively soft surface compared to jade. Often found as rounded river or beach stones in areas with volcanic history.
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