sedimentary

Quartz-rich sandstone

Quartz arenite (sandstone), likely iron-stained

AI-generated identification · may be incorrect

Composed mainly of quartz grains with minor feldspar and iron-oxide cement; tan to brown, granular, and nonmetallic with a dull to faintly sparkling luster. Quartz hardness is 7 Mohs, but the cemented rock is commonly unevenly friable; no obvious cleavage, typical specific gravity about 2.2–2.7.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand accumulated, was compacted, and cemented by silica or iron oxides in a sedimentary basin; the image alone cannot establish its geological age. Rounded grains and rusty coloration indicate weathering and oxidation after or during lithification.

Uses & applications

Used as building stone, aggregate, paving material, and silica source when sufficiently pure; this irregular specimen is primarily suitable for teaching or collecting rather than jewelry.

Geological facts

The glittering points are likely individual quartz grains or cement surfaces, not necessarily visible crystals. Iron oxides commonly produce the yellow-brown to reddish staining seen in weathered sandstone.

Field identification & locations

Identify it by its gritty texture, visible sand-sized grains, layered or porous fabric, and lack of strong crystal cleavage; a hand lens and dilute acid test (little or no fizz) help distinguish it from limestone. Common worldwide, especially in river, beach, desert, and marine sedimentary formations.