Schist

Physical Properties

Hardness: 3.5-4; Color: Grey, silver, or greenish-grey; Luster: Pearly to sub-metallic due to mica; Crystal structure: Foliated; Cleavage: Perfect basal cleavage in individual mica grains; Specific gravity: 2.7-2.8

Formation & Geological History

Formed through the regional metamorphism of shale or mudstone under intermediate to high temperatures and pressures. This transformational process aligns platy minerals like mica into thin, visible layers.

Uses & Applications

Primarily used as decorative stone in gardens, flagstone for walkways, and as a component in building facades. Not generally used as a structural material due to its tendency to split.

Geological Facts

The word schist is derived from the Greek s schistos, meaning 'easily split.' It represents a higher grade of metamorphism than slate or phyllite, but a lower grade than gneiss.

Field Identification & Locations

Identify it by its 'schistosity' or layered appearance and its distinct sparkle when turned in the light. It is commonly found in mountainous regions such as the Appalachian Mountains or the Alps.

Identified on: 5/1/2026

Mode: Standard