metamorphic or sedimentary

Greenstone / Glauconitic Siltstone

Metabasalt or Glauconite-rich Sedimentary Rock

AI-generated identification · may be incorrect

Hardness: 3-6 (depending on mineralogy); Color: Dull green to teal-grey; Luster: Earthy to waxy; Texture: Fine-grained, smooth water-worn surface.

Hardness: 3-6 (depending on mineralogy)
Color: Dull green to teal-grey
Luster: Earthy to waxy

Identified April 10, 2026More metamorphic or sedimentary →

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Physical properties

Hardness: 3-6 (depending on mineralogy); Color: Dull green to teal-grey; Luster: Earthy to waxy; Texture: Fine-grained, smooth water-worn surface.

Formation & geological history

Usually formed from the low-grade metamorphism of mafic igneous rocks (forming greenstone) or the accumulation of iron-rich silicates in marine environments (forming glauconite-rich siltstones).

Uses & applications

Commonly used as decorative landscaping stones, road aggregate, and sometimes as a pigment (green earth). High-quality greenstone is used for carving.

Geological facts

Greenstone belts represent some of the oldest known geological formations on Earth, documenting early tectonic processes millions to billions of years ago.

Field identification & locations

Identify in the field by its distinct greenish hue and fine-grained texture. Often found as rounded river or beach cobbles. Non-reactive to weak acids.