sedimentary

Graywacke with Quartz Vein

Lithic Sandstone (Graywacke)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs scale); Color: Dirty gray to brownish-green; Luster: Dull/Earthy; Structure: Clastic, fine to medium-grained; Cleavage: None; Specific Gravity: 2.6-2.7

Hardness: 6-7 (Mohs scale)
Color: Dirty gray to brownish-green
Luster: Dull/Earthy

Identified May 25, 2026More sedimentary →

Explore Graywacke with Quartz Vein in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6-7 (Mohs scale); Color: Dirty gray to brownish-green; Luster: Dull/Earthy; Structure: Clastic, fine to medium-grained; Cleavage: None; Specific Gravity: 2.6-2.7

Formation & geological history

Formed from the rapid deposition of poorly sorted sediment in deep-marine environments, often via turbidity currents. This specimen features a secondary quartz vein formed when silica-rich fluids filled a fracture long after the rock solidified.

Uses & applications

Used primarily as road base, railroad ballast, and coarse aggregate in construction; occasionally used for paving stones.

Geological facts

Graywacke is often called 'dirty sandstone' because of its high clay content and variety of rock fragments. It is a key indicator of ancient tectonic activity and underwater landslides.

Field identification & locations

Identify by its gray color, extreme hardness compared to other sandstones, and the presence of poorly sorted grains. Commonly found in coastal or mountainous regions with history of oceanic subduction.