Sandstone (with Limonite staining)

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Yellow, orange, tan, or brown; Luster: Dull/Earthy; Crystal structure: Clastic (grain-supported); Cleavage: None; Specific gravity: 2.2-2.8

Formation & Geological History

Formed through the accumulation of sand-sized mineral grains (usually quartz) that are cemented together by silica, calcium carbonate, or iron oxides. This yellow coloring indicates secondary staining by limonite or goethite through groundwater weathering.

Uses & Applications

Used primarily as building stone, flagstone, and in the production of glass and concrete. Fine-grained specimens are occasionally used for carvings.

Geological Facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. The vibrant yellow and orange colors seen here are the same mineral pigments used by early humans for cave paintings.

Field Identification & Locations

Identify in the field by its gritty texture (feels like sandpaper) and visible layers or bedding. It is found worldwide in deserts, riverbeds, and coastal regions. Collectors look for unique banding or fossil inclusions.

Identified on: 5/8/2026

Mode: Standard