metamorphic
Banded Slate
Metamorphic Argillite / Slate
Hardness: 3 to 4 on the Mohs scale; Color: Dark greyish-green with lighter yellowish banding; Luster: Dull to earthy; Crystal structure: Fine-grained, foliated metamorphic rock; Cleavage: Excellent slaty cleavage; Specific gravity: 2.7 to 2.8
- Hardness
- 3 to 4 on the Mohs scale
- Color
- Dark greyish-green with lighter yellowish banding
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 to 4 on the Mohs scale; Color: Dark greyish-green with lighter yellowish banding; Luster: Dull to earthy; Crystal structure: Fine-grained, foliated metamorphic rock; Cleavage: Excellent slaty cleavage; Specific gravity: 2.7 to 2.8
Formation & geological history
Formed through the regional metamorphism of fine-grained sedimentary rocks such as shale or clay siltstone under moderate pressure and low temperature conditions, often dating back hundreds of millions of years.
Uses & applications
Used historically for roofing tiles, blackboards, and flooring; also commonly collected as a polished or water-worn decorative stone.
Geological facts
The distinct bands visible on this specimen are relict bedding planes, representing original layers of sediment deposited prior to metamorphism and deformation.
Field identification & locations
Easily identified by its fine-grained texture, smooth water-worn shape, and characteristic parallel color banding. Commonly found in riverbeds, glacial tills, and mountainous metamorphic terrains.
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