sedimentary
Sandstone (Quartzite-rich Cobble)
Clastic sedimentary rock (primarily SiO2)
Hardness: 6-7 (Mohs scale); Color: Tan, buff, or grayish-yellow; Luster: Dull or earthy; Crystal structure: Granular/clastic; Cleavage: None; Specific gravity: approx. 2.6
- Hardness
- 6-7 (Mohs scale)
- Color
- Tan, buff, or grayish-yellow
- Luster
- Dull or earthy
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Tan, buff, or grayish-yellow; Luster: Dull or earthy; Crystal structure: Granular/clastic; Cleavage: None; Specific gravity: approx. 2.6
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. This specific rounded shape indicates transport in high-energy water environments like riverbeds or coastal zones during the Quaternary period.
Uses & applications
Used primarily as construction aggregate, landscape stone, and in glass manufacturing if silica content is high high. This specific weathered cobble is mostly used for decorative landscaping.
Geological facts
Sandstone preserves records of ancient environments, such as desert dunes and river deltas. Rounded specimens like this are often referred to as 'river rocks' and have been smoothed by thousands of years of abrasion.
Field identification & locations
Identify in the field by its gritty texture (feels like sandpaper) and visible sand grains. Commonly found in dry riverbeds, glacial tills, and sedimentary basins. It will not fizz with acid unless it has a calcite cement.
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