Graywacke is a “dirty” sandstone distinguishable by its angular to subangular clasts and minor silt/mud content. It often hosts graded beds.
Rock group | Sedimentary |
Origin | Clastic/detrital |
Particle size (Wentworth) | 0.0625 – 2 mm |
Graywacke in Hand Sample
Silurian-aged graywacke (from Siccar Point!)
Ordovician-aged Martinsburg Formation graywacke
Turbidites from Patagonia
Graywacke in Thin Section
Graywacke, plane polars
Graywacke, crossed polars
![](http://blogs.nvcc.edu/mineralogy/files/2018/10/50HD0010-1024x768.jpg)
![](http://blogs.nvcc.edu/mineralogy/files/2018/10/50HD0012-1024x768.jpg)