metamorphic
Greenschist
Greenschist (containing Chlorite, Actinolite, and Epidote)
Hardness: 3.5 to 4.5; Color: Dull green to dark gray-green; Luster: Pearly to earthy; Crystal Structure: Foliated or schistose texture; Cleavage: Perfect in one direction (slaty/schistose); Specific Gravity: 2.8-3.0.
- Hardness
- 3
- Color
- Dull green to dark gray-green
- Luster
- Pearly to earthy
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Physical properties
Hardness: 3.5 to 4.5; Color: Dull green to dark gray-green; Luster: Pearly to earthy; Crystal Structure: Foliated or schistose texture; Cleavage: Perfect in one direction (slaty/schistose); Specific Gravity: 2.8-3.0.
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) at low temperatures (300-450 degrees Celsius) and moderate pressures. Commonly associated with mountain-building events in orogenic belts.
Uses & applications
Used primarily as decorative stone, for garden landscaping, or as crushed stone for road construction. Occasionally used in sculpture if the specimen lacks excessive fracturing.
Geological facts
The green color is primarily due to the presence of chlorite, epidote, and actinolite. The 'Greenschist Facies' is a major classification tool used by geologists to describe a specific range of metamorphic conditions.
Field identification & locations
Identify by its characteristic green hue and fine-grained, foliated texture. It often splits into thin, flat plates. Commonly found in the Appalachian Mountains, the Alps, and other ancient mountain ranges.
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