metamorphic
Greenstone
Greenschist / Meta-basalt
Hardness: 5-6 on Mohs scale; Color: Dull grayish-green to dark green; Luster: Dull to sub-vitreous; Structure: Massive or slightly foliated; Gravity: 2.8-3.0.
- Hardness
- 5-6 on Mohs scale
- Color
- Dull grayish-green to dark green
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 5-6 on Mohs scale; Color: Dull grayish-green to dark green; Luster: Dull to sub-vitreous; Structure: Massive or slightly foliated; Gravity: 2.8-3.0.
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) at low temperatures and pressures. Often associated with ancient volcanic arcs.
Uses & applications
Historically used for stone tools (axes); currently used as crushed stone for construction, road base, and decorative landscaping rock.
Geological facts
The green color is primarily due to the presence of chlorite, epidote, or actinolite minerals. Greenstones are often found in some of the oldest parts of the Earth's crust known as Greenstone Belts.
Field identification & locations
Identify by its characteristic 'sea-green' hue and lack of distinct crystals or layering compared to schist. Commonly found in riverbeds or coastal areas near ancient tectonic plate boundaries.
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