metamorphic
Greenschist
Greenschist (chlorite-epidote schist)
Hardness: 3.5-4.5; Color: Dull grayish-green to emerald green; Luster: Pearly to earthy; Crystal structure: Foliated (schistose); Cleavage: Perfect in one direction due to mica content; Specific gravity: 2.8-3.0.
- Hardness
- 3
- Color
- Dull grayish-green to emerald green
- Luster
- Pearly to earthy
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3.5-4.5; Color: Dull grayish-green to emerald green; Luster: Pearly to earthy; Crystal structure: Foliated (schistose); Cleavage: Perfect in one direction due to mica content; Specific gravity: 2.8-3.0.
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) at temperatures of 300 to 450 degrees Celsius and moderate pressure. This process typically occurs in tectonic subduction zones or orogenic belts.
Uses & applications
Primarily used in construction as a decorative facing stone, garden landscaping, or as crushed aggregate for road foundations. Occasionally used for small carvings or as a source of industrial minerals.
Geological facts
The green color comes from minerals such as chlorite, actinolite, and epidote which form specifically under low-temperature metamorphic conditions known as the 'Greenschist Facies'. This rock signifies that the parent rock was once deep underground but never reached high temperatures.
Field identification & locations
Identify by its characteristic greenish hue and 'platy' or flaky foliation that causes it to split into thin layers. It often feels slightly greasy or soapy to the touch due to chlorite. Common in the Appalachian Mountains and the Scottish Highlands.
More like this
