Greenstone

Physical Properties

Hardness: 3.5 to 5 on Mohs scale; Color: Dull green, grey-green, or olive; Luster: Pearly to dull; Structure: Often foliated or schistose, with a fine-grained texture; Cleavage: Good in one direction; Specific Gravity: 2.8 to 3.0

Formation & Geological History

Formed through regional metamorphism of mafic igneous rocks (like basalt) under low-temperature and high-pressure conditions, typically in subduction zones or orogenic belts. Many greenstone belts are Archean in age.

Uses & Applications

Used historically for stone tools and weapons (axes); currently used as a decorative stone in landscaping, for crushed stone in construction, or occasionally for carving and jewelry.

Geological Facts

Greenstone belts are significant in geology because they often contain major gold, silver, and copper deposits. The green color is primarily due to the presence of minerals like chlorite, actinolite, and epidote.

Field Identification & Locations

Identify in the field by its characteristic greenish hue and fine-grained, tough texture that is difficult to break. It is commonly found in ancient shield areas like the Canadian Shield or Western Australia.

Identified on: 5/2/2026

Mode: Standard