Greenstone / Greenschist

Hardness: 3.5-5.5 (Mohs scale), Color: dull green to grayish-green with rusty iron staining, Luster: dull to silky, Structure: fine-grained to weakly foliated, Specific Gravity: 2.8-3.0

Formed through low-grade metamorphism (green-schist facies) of mafic igneous rocks like basalt or gabbro under high pressure and low temperature conditions. Common in ancient mountain belts.

Historically used for stone tools (celts) and axes. Modern uses include decorative gravel, crushed stone for construction, and as a dimension stone for architectural accents.

The green color is primarily due to the presence of chlorite, actinolite, and epidote minerals. It is a key indicator of specific metamorphic zones in historical geology.

Look for a distinct greenish hue that differentiates it from gray river stones. It is often found in glacial till, riverbeds in metamorphic terrains, and along ancient plate boundaries. Identification is confirmed by a lack of vigorous reaction to acid.