Metamorphic (low-grade)

Greenstone (possibly Basalt or Greenschist)

Greenschist (composed primarily of chlorite, actinolite, and epidote)

Hardness: 6-7 on Mohs scale; Color: Dark forest green to grayish-green; Luster: Dull to waxy; Texture: Fine-grained, often smooth or water-worn; Structure: Non-foliated to weakly foliated.

Hardness: 6-7 on Mohs scale
Color: Dark forest green to grayish-green
Luster: Dull to waxy

Identified March 14, 2026More metamorphic (low-grade) →

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Physical properties

Hardness: 6-7 on Mohs scale; Color: Dark forest green to grayish-green; Luster: Dull to waxy; Texture: Fine-grained, often smooth or water-worn; Structure: Non-foliated to weakly foliated.

Formation & geological history

Formed through the low-grade metamorphism of mafic igneous rocks (like basalt) under low temperature and high pressure. Often found in ancient orogenic belts or oceanic crust that has been subducted and exhaled.

Uses & applications

Historically used for making stone tools (axes and adzes) because of its toughness. Currently used for landscaping, crushed stone for construction, and occasionally for minor jewelry or cabochons if the color is vibrant.

Geological facts

Many Neolithic 'celt' axes were carved from greenstone due to its resiliency and lack of cleavage planes, making it difficult to shatter. In New Zealand, a specific type of greenstone called Pounamu is considered sacred by the Māori.

Field identification & locations

Identify in the field by its distinct green hue (visible when wet), high density, and hardness (it should not be scratched by a steel knife). Commonly found in riverbeds or coastal areas near tectonic plate boundaries.

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Shale or Argillite

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Slate

Low-grade Metamorphic Rock

metamorphic

Greenish Metamorphic Rock (likely containing epidote or chlorite)

Metamorphic rock, possibly epidosite or greenstone

Metamorphic

Greenschist

Chlorite schist

metamorphic