Sandstone

Physical Properties

Hardness: 6-7 (individual quartz grains); Color: Tan, beige, or brown; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None (breaks across grains); Specific gravity: 2.0-2.6

Formation & Geological History

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments over millions of years. This usually occurs in desert, river, or ocean environments through a process called lithification.

Uses & Applications

Extensively used in construction for flagstone, paving, and building materials. In industry, it is a source of silica for glass manufacturing and a common reservoir for ground water and petroleum.

Geological Facts

Sandstone is one of the most common types of sedimentary rock and accounts for about 20% of all sedimentary rocks on Earth. The famous 'Red Rocks' in Colorado are composed of iron-rich sandstone.

Field Identification & Locations

Identify in the field by its 'sandpaper' feel when rubbed. It is commonly found in sedimentary basins and canyons. For collectors, look for unique patterns like ripple marks or cross-bedding indicating ancient water flow.

Identified on: 4/22/2026

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