Graywacke

Graywacke is a “dirty” sandstone distinguishable by its angular to subangular clasts and minor silt/mud content. It often hosts graded beds.

Properties
Rock group Sedimentary
Origin Clastic
Particle size (Wentworth) 0.0625 – 2 mm

Graywacke in Hand Sample

Silurian-aged graywacke (from Siccar Point!)

Ordovician-age Martinsburg Formation graywacke

Turbidites from Patagonia

Graywacke in Thin Section

Graywacke, plane polars

Graywacke, crossed polars

Graywacke, plane polars
Graywacke, crossed polars