Sandstone (with Concretion)

Physical Properties

Hardness: 6-7 (Mohs scale for quartz grains); Color: Tan, brown, buff; Luster: Dull or earthy; Structure: Clastic, granular; Cleavage: None; Specific Gravity: 2.3-2.4

Formation & Geological History

Formed through the accumulation and cementation of mineral particles or rock fragments (silt and sand). The rounded feature is a concretion formed by the precipitation of mineral cement in the spaces between particles.

Uses & Applications

Used primarily as a construction material (dimension stone), in glass manufacturing (if high silica), and as a reservoir rock for oil, gas, and water.

Geological Facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. Concretions found within them are often mistaken for fossils or meteorites due to their unusual shapes.

Field Identification & Locations

Identify in the field by its gritty texture (feels like sandpaper) and visible sand grains. Concretions will appear as harder, distinct masses within the softer surrounding layers.

Identified on: 4/26/2026

Mode: Standard