metamorphic
Greenschist
Chlorite-actinolite schist
Hardness 2-3.5 on Mohs scale; Color is dark green to greyish-green; Luster is pearly to dull; Texture is foliated (schistose) with fine-grained mineral alignment; Cleavage is excellent in one direction due to mica/chlorite content.
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Physical properties
Hardness 2-3.5 on Mohs scale; Color is dark green to greyish-green; Luster is pearly to dull; Texture is foliated (schistose) with fine-grained mineral alignment; Cleavage is excellent in one direction due to mica/chlorite content.
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) under high pressure and low temperature conditions. Common in orogenic belts and subduction zones.
Uses & applications
Used as a decorative stone in gardening, as building veneers, and occasionally in the production of floor tiles. Historically used for making stone tools in some cultures.
Geological facts
Greenschist gets its name specifically from the presence of green minerals like chlorite, epidote, and actinolite. It defines a specific 'Greenschist Facies' in metamorphic geology reflecting a temperature range of 300 to 450 degrees Celsius.
Field identification & locations
Identify in the field by its distinct green hue, flaky/foliated texture, and relative softness (it can often be scratched with a copper penny or knife). Found commonly in the Appalachian Mountains, Alps, and Scottish Highlands.
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