metamorphic
Greenstone with Quartz Veining
Metamorphosed Mafic Igneous Rock
Hardness: 6-7 (Mohs scale); Color: Dull green, olive, or grayish-green with white/light gray veins; Luster: Dull to earthy; Texture: Fine-grained, microcrystalline.
- Hardness
- 6-7 (Mohs scale)
- Luster
- Dull to earthy
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Dull green, olive, or grayish-green with white/light gray veins; Luster: Dull to earthy; Texture: Fine-grained, microcrystalline.
Formation & geological history
Formed through the regional metamorphism of mafic igneous rocks (like basalt) under high pressure and low temperature conditions, typical of subduction zones or mountain-building environments.
Uses & applications
Primarily used as road aggregate, crushed stone for construction, and occasionally for ornamental garden stones or lapidary practice for beginners.
Geological facts
The green color is primarily due to the presence of chlorite, epidote, and actinolite minerals. Greenstones are often found in very old geological basement complexes known as 'greenstone belts' which can be billions of years old.
Field identification & locations
Look for a heavy, dense, green-colored rock that doesn't scratch easily. It is commonly found in ancient mountain ranges, riverbeds in glacial regions, or coastal areas with tectonic history.
