metamorphic

Greenstone (Metabalt)

Chlorite-actinolite schist (Greenstone)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs); Color: Dark green to grey-green; Luster: Dull to waxy; Texture: Fine-grained, often massive or foliated; Specific Gravity: 2.8-3.0.

Hardness: 6-7 (Mohs)
Color: Dark green to grey-green
Luster: Dull to waxy

Identified July 18, 2026More metamorphic →

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Physical properties

Hardness: 6-7 (Mohs); Color: Dark green to grey-green; Luster: Dull to waxy; Texture: Fine-grained, often massive or foliated; Specific Gravity: 2.8-3.0.

Formation & geological history

Formed through low-grade regional metamorphism of mafic igneous rocks like basalt or gabbro, occurring at depths where heat and pressure alter the mineralogy to include chlorite and epidote.

Uses & applications

Historically used for making stone tools (celts and axes); modernly used for decorative stone, construction aggregate, and as a landscaping material.

Geological facts

The green color is primarily due to the presence of the minerals chlorite, epidote, and actinolite. Many greenstones are billions of years old, forming the 'greenstone belts' of ancient continental shields.

Field identification & locations

Identify in the field by its distinct greenish hue and hardness (won't be scratched easily by steel). Common in ancient tectonic plate boundaries and riverbeds within metamorphic terrains.