metamorphic
Slate
Metamorphic Pelitic Rock
Hardness: 3-4 on the Mohs scale; Color: typically dark gray to black, but can be green, red, or purple; Luster: dull to earthy; Crystal structure: fine-grained, foliated (slate cleavage); Specific gravity: 2.6-2.8
- Hardness
- 3-4 on the Mohs scale
- Luster
- dull to earthy
Identified More metamorphic →
Explore Slate in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3-4 on the Mohs scale; Color: typically dark gray to black, but can be green, red, or purple; Luster: dull to earthy; Crystal structure: fine-grained, foliated (slate cleavage); Specific gravity: 2.6-2.8
Formation & geological history
Formed through low-grade regional metamorphism of pelitic sedimentary rocks, predominantly shale or mudstone, subjected to moderate heat and directed pressure. Geological age varies widely depending on the formation region, spanning from the Precambrian to the Paleozoic and younger.
Uses & applications
Used extensively in construction for roofing tiles, flooring, and exterior cladding, as well as in traditional blackboards, billiard tables, and as a decorative stone in landscaping.
Geological facts
Slate's prominent 'slaty cleavage' allows it to be split into very thin, flat sheets, a property that has made it a crucial building material for centuries.
Field identification & locations
Found in mountainous regions and areas with ancient orogenic (mountain-building) events. Identified by its fine-grained texture, distinct planar cleavage, and dull luster.
More like this
