metamorphic
Green Schist (Greenschist)
Greenschist facies metamorphic rock
Hardness: 3.5-4.5 on Mohs scale; Color: Green to dark green with dark mineral bands; Luster: Dull to pearly/silky on foliation planes; Crystal Structure: Phaneritic (visible crystals) with schistose foliation; Components: Chlorite, actinolite, and epidote.
- Hardness
- 3
- Color
- Green to dark green with dark mineral bands
- Luster
- Dull to pearly/silky on foliation planes
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Physical properties
Hardness: 3.5-4.5 on Mohs scale; Color: Green to dark green with dark mineral bands; Luster: Dull to pearly/silky on foliation planes; Crystal Structure: Phaneritic (visible crystals) with schistose foliation; Components: Chlorite, actinolite, and epidote.
Formation & geological history
Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) at relatively low temperatures (300 to 450 degrees Celsius) and moderate pressures. Commonly associated with orogenic belts and subduction zones.
Uses & applications
Primarily used as a decorative stone in landscaping, for construction fill, and occasionally as a minor building stone. Also significant in geological studies to identify metamorphic facies and tectonic history.
Geological facts
The green color is primarily due to the presence of the minerals chlorite, actinolite, and epidote. It represents a specific 'facies' in geology, indicating the specific P-T (pressure-temperature) conditions that existed during the rock's formation.
Field identification & locations
Identified by its distinctive green color and platey/flaky foliation (schistosity). It is common in mountain ranges like the Alps, the Appalachians, and the Scottish Highlands. Collectors look for well-defined mineral banding and sheen.
