metamorphic
Greenschist
Greenschist (Chlorite Schist)
Hardness: 3.5-5 Mohs; Color: Dull green to dark forest green with white/cream calcite or quartz veinlets; Luster: Dull, waxy, to slightly silky; Structure: Foliated, fine-grained metamorphic texture; Cleavage: Poor to moderate along schistosity planes
- Hardness
- 3
- Luster
- Dull, waxy, to slightly silky
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Physical properties
Hardness: 3.5-5 Mohs; Color: Dull green to dark forest green with white/cream calcite or quartz veinlets; Luster: Dull, waxy, to slightly silky; Structure: Foliated, fine-grained metamorphic texture; Cleavage: Poor to moderate along schistosity planes
Formation & geological history
Formed via regional metamorphism of mafic igneous rocks (such as basalt or gabbro) under low-temperature and low-to-moderate pressure conditions (greenschist facies), commonly in subduction zones or orogenic belts.
Uses & applications
Used occasionally as a decorative stone, stream pebbles for landscaping, or as aggregate in road building. Collectible for regional geology specimens.
Geological facts
The green color is primarily due to chlorite, actinolite, and epidote minerals formed during metamorphism. It often contains thin white cross-cutting veins of quartz or calcite that were deposited by fluid activity during deformation.
Field identification & locations
Identify in the field by its distinctive muted green matrix patterned with light-colored streaks or veins and fine foliated texture. Commonly found along active or ancient mountain belts and riverbeds in tectonic regions.
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