sedimentary

Quartz Pebble in Sandstone matrix

Quartz Conglomerate (SiO2 matrix)

Hardness 6.5 to 7 on the Mohs scale. Colors range from grayish-brown to translucent milky white. Features a dull to glassy luster, granular texture in the surrounding matrix, and a smooth, rounded quartz vein or pebble clast embedded within.

Identified July 25, 2026More sedimentary →

Explore Quartz Pebble in Sandstone matrix in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed in high-energy sedimentary environments such as river beds, beach zones, or alluvial fans where rounded quartz pebbles were deposited alongside coarse sand grains and subsequently cemented together with silica, iron oxide, or calcite under pressure.

Uses & applications

Primarily collected as a interesting geological specimen, educational pebble, or used in landscaping and construction aggregate when quarried in bulk.

Geological facts

Quartz pebbles like this are extremely durable and resistant to both chemical and mechanical weathering. As the softer surrounding rock erodes over geological time, the hard quartz clasts are left behind as smooth river stones.

Field identification & locations

Can be easily identified in the field by the distinct smooth, hard, vitreous quartz inclusions contrasting with the rougher, sand-sized surrounding matrix. Common along riverbeds, glacial tills, and ancient sedimentary formations worldwide.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Sedimentary Sandstone

Arenite (Sedimentary Rock)

sedimentary

Fossiliferous Concretion

Septarian Concretion containing Brachiopods/Crinoids

fossil

Shale

Shale (clastic sedimentary rock)

sedimentary

Shale

Argillaceous sedimentary rock

sedimentary

Mudstone

Argillite / Siliciclastic sedimentary rock

sedimentary