Greenstone

Physical Properties

Hardness: 5-7 (Mohs scale); Color: Olive-green to forest-green; Luster: Dull to waxy; Crystal Structure: Fine-grained, often foliated; Specific Gravity: 2.85-3.00.

Formation & Geological History

Formed through low-grade regional metamorphism of mafic igneous rocks like basalt or gabbro under high pressure and low temperatures, typically in subduction zones or mountain-building environments.

Uses & Applications

Used historically for stone tools and weapons; currently used as decorative landscaping stone, crushed aggregate in construction, and occasionally for carving ornaments.

Geological Facts

The green color is primarily due to the presence of minerals like chlorite, epidote, and actinolite. The term Greenstone belt is used in geology to describe large areas containing these rocks, which often host gold and copper deposits.

Field Identification & Locations

Identify in the field by its distinct green hue and toughness compared to other rocks. Common in ancient cratons and volcanic coastal regions. It is often found as polished river or beach stones.

Identified on: 4/29/2026

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