Greenstone or Chlorite Schist

Physical Properties

Hardness: typically 2-4 (Mohs), depending on exact composition. Color: grayish green to dark green. Luster: dull to slightly silky or pearly due to micaceous minerals. Crystal structure: foliated (schistose) or massive. Cleavage: excellent in one direction if schistose.

Formation & Geological History

Formed through low-grade regional metamorphism of mafic igneous rocks (like basalt) or clay-rich sediments. Typically contains chlorite, epidote, and actinolite which impart the green color.

Uses & Applications

Often used as aggregate, decorative stone, or for landscaping. Rarely used for structural purposes due to foliation.

Geological Facts

Greenstone belts are often associated with ancient Archean cratons and can host significant gold and base metal deposits along shear zones.

Field Identification & Locations

Identified by its greenish color, foliation (layered structure), and relatively soft nature. Commonly found in areas of ancient mountain building and continental shields.

Identified on: 4/25/2026

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