Greywacke
Rock
Also called Graywacke and Wacke
About it
Hard, dark grey sandstone of poorly sorted sand, rock fragments, and a muddy matrix, laid down by underwater turbidity currents. Common in old mountain belts such as Wales, the Southern Uplands of Scotland, and New Zealand.
- Type
- Rock (sedimentary)
- Group
- Sedimentary (clastic)
- Specific gravity
- 2.5–2.8
- Lustre
- dull
- Colours
- dark grey, greenish grey, black
- Transparency
- opaque
Typical values: real specimens vary. For more, see mindat.org.