Greenschist

Physical Properties

Hardness: 2-3.5 (on Mohs scale); Color: Dull green, grayish-green; Luster: Pearly to earthy; Structure: Foliated or schistose with visible layering; Cleavage: Perfect in one direction due to mica/chlorite content.

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. Common in mountain-building zones.

Uses & Applications

Used as decorative stone in gardens, historical building material, and occasionally as a source for magnesium-rich minerals.

Geological Facts

The green color is primarily due to the presence of the minerals chlorite, epidote, and actinolite. It is a key indicator for geologists determining the pressure and temperature conditions of ancient tectonic events.

Field Identification & Locations

Identify in the field by its distinct green hue, flaky or 'schistose' texture that splits into thin plates, and its relative softness compared to other metamorphic rocks. Often found in Appalachian or Alpine regions.

Identified on: 4/26/2026

Mode: Standard