metamorphic
Greenstone
Metabasalt or Greenschist (often contains Chlorite, Actinolite, and Epidote)
Hardness: 6-7 Mohs; Color: Pale to dark green; Luster: Dull to waxy; Structure: Finely crystalline to foliated; SG: 2.8-3.0
- Hardness
- 6-7 Mohs
- Color
- Pale to dark green
- Luster
- Dull to waxy
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Physical properties
Hardness: 6-7 Mohs; Color: Pale to dark green; Luster: Dull to waxy; Structure: Finely crystalline to foliated; SG: 2.8-3.0
Formation & geological history
Formed via low-grade regional metamorphism of mafic igneous rocks (like basalt) under high pressure and relatively low temperatures, often in subduction zones.
Uses & applications
Used historically for stone tools and weapons (like adzes), today used as crushed stone for construction, decorative landscaping, and occasionally lapidary work.
Geological facts
The green color is primarily due to the presence of chlorite, epidote, or actinolite. Some greenstones are over 2.5 billion years old and belong to ancient greenstone belts.
Field identification & locations
Identify by its distinct greenish hue and hardness (cannot be scratched by a steel nail). Commonly found in mountain belts and coastal regions with ancient tectonic activity.
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