metamorphic
Greenschist
Greenschist (chlorite schist)
Hardness: 3.5 to 4.5; Color: Grey-green to dark green; Luster: Dull to silky; Crystal structure: Foliated, fine-grained; Cleavage: Good slaty cleavage; Specific Gravity: 2.8 to 3.0
- Hardness
- 3
- Color
- Grey-green to dark green
- Luster
- Dull to silky
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Physical properties
Hardness: 3.5 to 4.5; Color: Grey-green to dark green; Luster: Dull to silky; Crystal structure: Foliated, fine-grained; Cleavage: Good slaty cleavage; Specific Gravity: 2.8 to 3.0
Formation & geological history
Formed through the regional metamorphism of mafic igneous rocks (like basalt) under low temperature and moderate pressure conditions. Occurs in mountain belts and mid-ocean ridges.
Uses & applications
Used as a construction material for flagstones, decorative building facades, and as an additive in roofing materials. Historically used for making tools and carvings.
Geological facts
The green color is primarily due to the presence of minerals like chlorite, epidote, and actinolite. The metamorphic facies associated with these conditions is known as the Greenschist Facies.
Field identification & locations
Identify in the field by its distinct green hue and foliated (layered) texture that may cause it to split into thin sheets. Common in areas with old mountain ranges like the Appalachians or the Alps.
