sedimentary

Shale with Quartz Vein

Argillaceous Shale with Silicon Dioxide Vein

AI-generated identification · may be incorrect

Grey to black fine-grained sedimentary rock, often fissile, relatively soft (Mohs 2-3). The vein is harder, lighter in color, typically quartz (Mohs 7).

Identified September 21, 2026More sedimentary →

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Physical properties

Grey to black fine-grained sedimentary rock, often fissile, relatively soft (Mohs 2-3). The vein is harder, lighter in color, typically quartz (Mohs 7).

Formation & geological history

Shale forms from the compaction of silt and clay-sized mineral particles over millions of years in quiet water environments. The quartz vein formed later when silica-rich fluids filled a fracture in the shale.

Uses & applications

Shale is used as a source material in the ceramics industry and for making brick, tile, and pottery. Quartz veins are often prospected for gold or other valuable minerals.

Geological facts

The presence of a vein indicates tectonic activity or stress that fractured the host rock after its formation, allowing mineral-laden water to precipitate quartz.

Field identification & locations

Identify by the fine-grained, laminated texture of the dark shale contrasting with the hard, crystalline lighter vein. Commonly found in areas with sedimentary rock formations that have undergone some structural deformation.