Sandstone (Glacial Cobble)

Physical Properties

Hardness: 6-7 (Mohs scale); Color: Tan, buff, or light grey with earthy tones; Luster: Dull/Earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None (granular fracture); Specific Gravity: 2.2-2.8

Formation & Geological History

Formed through the accumulation and cementation of mineral particles or rock fragments (sand) over millions of years. This specific specimen appears to be a stream or glacial cobble, rounded by mechanical weathering during transport.

Uses & Applications

Commonly used in large scale construction as a building material, road base, or decorative landscaping stone. In industry, high-purity sandstone is a source of silica for glassmaking.

Geological Facts

Sandstone accounts for roughly 20 to 25 percent of all sedimentary rocks on Earth. It often acts as a significant aquifer, holding large quantities of groundwater due to its porosity.

Field Identification & Locations

Identify in the field by its sandpaper-like texture (gritty to the touch) and visible sand grains. These smoothed varieties are often found in riverbeds or glacial till deposits.

Identified on: 4/20/2026

Mode: Standard