metamorphic
Greenschist
Chlorite-actinolite schist
Hardness: 3.5-4.5 (Mohs scale); Color: dark green to grayish-green; Luster: Pearly or vitreous; Crystal structure: Foliated/Schistose; Cleavage: Perfect in one direction due to mica/chlorite content.
- Hardness
- 3
- Color
- dark green to grayish-green
- Luster
- Pearly or vitreous
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Physical properties
Hardness: 3.5-4.5 (Mohs scale); Color: dark green to grayish-green; Luster: Pearly or vitreous; Crystal structure: Foliated/Schistose; Cleavage: Perfect in one direction due to mica/chlorite content.
Formation & geological history
Formed through regional metamorphism of mafic igneous rocks (like basalt) or volcanic sediment under low temperature and moderate pressure conditions. Typically associated with mountain building and subduction zones.
Uses & applications
Commonly used as ornamental stone, building cladding, crushed stone for road construction, and occasionally for carving or in landscaping.
Geological facts
The green color is primarily due to the presence of chlorite, epidote, or actinolite. It defines a specific metamorphic facies (the greenschist facies) used by geologists to determine past pressure and temperature conditions of the Earth's crust.
Field identification & locations
Identify by its characteristic green color and scaly or flaky (schistose) texture. Found in metamorphic belts worldwide, such as the Appalachian Mountains, the Alps, and New Zealand.
