Green Slate (Greenstone)

Physical Properties

Hardness: 2.5-4 (Mohs scale), Color: Dull olive green, Luster: Waxy to earthy, Structure: Foliated with fine-grained slaty cleavage, Specific Gravity: 2.7-2.8

Formation & Geological History

Formed from the low-grade metamorphism of shale or mudstone under tectonic pressure and low temperatures, typically in convergent plate boundaries.

Uses & Applications

Used in roofing, flooring, billiards tables, and as high-quality decorative garden stones or aquarium pebbles.

Geological Facts

Slate is unique because it can be split into thin, flat sheets. The green color is primarily due to the presence of chlorite minerals formed during metamorphism.

Field Identification & Locations

Identified by its signature dull green color and parallel layers (foliation) that cause it to break in flat planes. Common in riverbeds and mountainous regions like Vermont, New York, and Wales.

Identified on: 5/20/2026

Mode: Standard