Sandstone (with Manganese staining)

Physical Properties

Hardness: 6-7 (Mohs); Color: Tan, beige with black dendritic/splotchy manganese staining; Luster: Dull/Earthy; Texture: Granular, sandpaper-like feel.

Formation & Geological History

Formed through the accumulation and cementation of sand-sized grains (quartz or feldspar), typically in river beds, deserts, or marine environments. The rounded shape indicates high levels of water erosion (fluvial transport).

Uses & Applications

Used in construction as a building stone or paving material; crushed for road base; silica source for glass making.

Geological Facts

The black coloration on the surface is likely 'desert varnish' or manganese oxide staining, which often forms on rocks exposed to the elements for long periods. Sandstone makes up about 20% of the sedimentary rocks on Earth.

Field Identification & Locations

Identify in the field by its gritty texture and visible sand grains. Common in riverbeds, canyons, and coastal outcrops. Helpful for understanding ancient water flow or wind patterns in an area.

Identified on: 4/23/2026

Mode: Standard