metamorphic (localized) or sedimentary

Slickenside in Limestone

Tectonized Limestone / Calcite (CaCO3)

Hardness: 3 (Mohs). Color: Grey to light green/white. Luster: Vitreous to pearly on the sheared surface. Structure: Striated, grooved, and polished surfaces (slickensides). Cleavage: Perfect rhombohedral in mineral veins.

Hardness: 3 (Mohs)
Color: Grey to light green/white
Luster: Vitreous to pearly on the sheared surface

Identified June 1, 2026More metamorphic (localized) or sedimentary →

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Physical properties

Formation & geological history

Formed along fault planes or fracture zones. High pressure and friction during tectonic movement cause the rock surfaces to grind against each other, creating polished, grooved textures. Often involves hydrothermal calcite precipitation in the crack.

Uses & applications

Primarily of geological and educational interest to study tectonic activity and fault movement. Calcite itself is used in cement, lime, and as a soil conditioner.

Geological facts

The grooves, or 'striae', on a slickenside tell geologists the exact direction the tectonic plates or rock masses were moving when the fault occurred. Some slickensides are so polished they look like mirrors ('slickenside mirrors').

Field identification & locations

Identify by the parallel linear grooves and polished feel on a flat plane within an otherwise rough rock. Common in seismic zones or mountain belts. Use a drop of white vinegar; if it fizzes, it is limestone/calcite.

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