sedimentary

Sandstone (Greywacke)

Sandstone (SiO2 enriched with lithic fragments)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs); Color: Grey-green to tan; Luster: Dull/Earthy; Crystal structure: Clastic (fine-grained); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65.

Hardness: 6-7 (Mohs)
Color: Grey-green to tan
Luster: Dull/Earthy

Identified March 21, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Mohs); Color: Grey-green to tan; Luster: Dull/Earthy; Crystal structure: Clastic (fine-grained); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65.

Formation & geological history

Formed through the accumulation and lithification of sand-sized grains, often in high-energy marine or fluvial environments. This specimen shows signs of rounded weathering through water erosion (beach or river pebble).

Uses & applications

Used primarily in construction as crushed stone or fill; decorative use in landscaping and aquariums; historically used for grindstones.

Geological facts

Sandstone accounts for roughly 20 to 25 percent of all sedimentary rocks in the Earth's crust. It is a critical reservoir rock for groundwater and petroleum.

Field identification & locations

Identify in the field by its 'sandpaper' texture and visible small grains. Commonly found on beaches, riverbeds, and in arid desert formations. Collectors look for unique banding or rounding.