Sandstone (likely Ferruginous)

Physical Properties

Hardness: 6-7 (individual grains); Color: terracotta/orange/red due to iron oxide; Luster: dull/earthy; Crystal structure: granular/clastic; Cleavage: none; Specific gravity: 2.2-2.8

Formation & Geological History

Formed through the accumulation of sand-sized mineral grains or rock fragments, subsequently lithified by mineral cement (silica or calcium carbonate) over millions of years. This specimen appears water-worn, potentially from a river or coastal environment.

Uses & Applications

Construction aggregate, architectural stone, decorative landscaping, and occasionally used for grindstones or oil/gas reservoirs due to porosity.

Geological Facts

The orange-red color is caused by the oxidation of iron-bearing minerals, essentially 'rusting' the rock. This specimen shows a smooth, rounded shape indicating significant transport by water.

Field Identification & Locations

Identify in the field by its gritty texture (feels like sandpaper) and visible sand grains. These are commonly found in desert basins, riverbeds, and coastal cliffs.

Identified on: 4/24/2026

Mode: Standard