metamorphic
Greenstone
Greenschist
Hardness: 3.5 to 4.5. Color: Dull green to dark forest green. Luster: Earthy to dull. Crystal Structure: Fine-grained, often foliated or massive. Specific Gravity: 2.7 to 3.0.
- Hardness
- 3
- Color
- Dull green to dark forest green
- Luster
- Earthy to dull
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Physical properties
Hardness: 3.5 to 4.5. Color: Dull green to dark forest green. Luster: Earthy to dull. Crystal Structure: Fine-grained, often foliated or massive. Specific Gravity: 2.7 to 3.0.
Formation & geological history
Formed through regional metamorphism of mafic igneous rocks (like basalt) under low temperature and moderate pressure conditions, typically in subduction zones.
Uses & applications
Historical use for stone tools and weapons (celt/axes); decorative stone, construction aggregate, and occasionally used in landscaping.
Geological facts
The green color comes from minerals like chlorite, epidote, and actinolite. The 'Greenstone Belt' areas are some of the oldest crustal features on Earth, containing rocks billions of years old.
Field identification & locations
Identify by its distinctive dull green hue and fine grain. Common in mountainous regions and ancient shield areas. Collectors look for pieces with interesting mineral inclusions.
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