Slate
Rock
About it
Fine-grained rock from shale that splits into thin, smooth, hard sheets that ring when tapped, with no visible grains. Quarried for roofs and blackboards in Wales, Vermont, and Newfoundland.
- Type
- Rock (metamorphic)
- Group
- Metamorphic (foliated)
- Specific gravity
- 2.7–2.9
- Lustre
- dull
- Colours
- grey, black, green, purple, red
- Transparency
- opaque
- Cleavage and fracture
- splits into thin, flat sheets (slaty cleavage)
Typical values: real specimens vary. For more, see mindat.org.