Sandstone (likely Greywacke or Lithic Sandstone)

Physical Properties

Hardness: 6-7 (Mohs scale); Color: Grey, brownish-grey, or tan; Luster: Dull/Earthy; Crystal structure: Clastic (grainy texture); Cleavage: None (grains are cemented together); Specific gravity: 2.6-2.7.

Formation & Geological History

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. Typically deposits in marine, river, or desert environments. This specimen appears to be weathered surface rock from the Phanerozoic eon.

Uses & Applications

Primary use in construction (crushed stone, road base), building material for pavers or walls, and occasionally as a reservoir rock for oil and gas.

Geological Facts

Sandstone accounts for roughly 20 to 25 percent of all sedimentary rocks in the Earth's crust. It is a key indicator for geologists in determining ancient environmental conditions like flow direction of prehistoric rivers.

Field Identification & Locations

Identify in the field by its 'gritty' feel, similar to sandpaper, and a lacks of visible bedding planes in the massive variety. Commonly found in outcroppings, river beds, and mountainous regions worldwide.

Identified on: 4/15/2026

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