Greenstone

Physical Properties

Hardness: 3.5-5 (Mohs scale); Color: Dull green, grayish-green, or forest green; Luster: Dull to earthy; Crystal structure: Fine-grained, sometimes foliated; Cleavage: Generally poor; Specific Gravity: 2.6-3.3

Formation & Geological History

Formed through the low-grade metamorphism of mafic igneous rocks (like basalt or gabbro) under relatively low temperatures and pressures, typically associated with regional metamorphism in orogenic belts.

Uses & Applications

Historically used for making stone tools (celts and axes) due to its toughness. Today it is used in construction as crushed stone, for ornamental garden rocks, and occasionally in rough jewelry or carvings.

Geological Facts

The 'green' in greenstone is caused by minerals like chlorite, epidote, and actinolite. The famous 'Great Wall of China' used greenstone in some of its sections, and it was a prized material for Neolithic tools in Europe and the Pacific.

Field Identification & Locations

Identify by its distinctive dull green color and relative softness compared to quartz. Look for it in areas of ancient volcanic activity and mountain belts. Often found as rounded river pebbles or coastal cobbles showing a smooth, waxy surface when wet.

Identified on: 4/21/2026

Mode: Standard