metamorphic
Greenstone
Metabasalt / Chlorite-Epidote Schist
Hardness: 5-6 (Mohs); Color: Pale to dark green; Luster: Dull to pearly; Structure: Fine-grained, often foliated or massive; Specific Gravity: 2.8-3.0.
- Hardness
- 5-6 (Mohs)
- Color
- Pale to dark green
- Luster
- Dull to pearly
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Physical properties
Hardness: 5-6 (Mohs); Color: Pale to dark green; Luster: Dull to pearly; Structure: Fine-grained, often foliated or massive; Specific Gravity: 2.8-3.0.
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) under high pressure and low temperature conditions, typical of subduction zones and ancient mountain belts.
Uses & applications
Used historically for stone tools like axes; currently used as crushed stone for construction, road base, and occasionally as decorative landscaping stone.
Geological facts
Greenstone belts represent some of the oldest known geological formations on Earth, dating back to the Archean Eon, often containing significant gold deposits.
Field identification & locations
Identify by its characteristic dull green hue caused by chlorite and epidote minerals. It is often found in ancient shield areas like the Canadian Shield or Western Australia.
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