sedimentary
Red Sandstone (Hematitic)
Clastic sedimentary rock (SiO2 with Fe2O3 inclusions)
Hardness: 6-7 (if quartz-rich); Color: Dark reddish-brown to maroon; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8
- Hardness
- 6-7 (if quartz-rich)
- Color
- Dark reddish-brown to maroon
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (if quartz-rich); Color: Dark reddish-brown to maroon; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of mineral particles or rock fragments. The red color suggests deposition in an oxygen-rich environment where iron minerals oxidized (rusted). Often associated with ancient river beds or desert dunes.
Uses & applications
Used in landscaping, construction as a building stone (brownstone), and as a decorative garden pebble due to its smooth water-worn texture.
Geological facts
The red color is specifically due to a thin coating of iron oxide (hematite) around the individual sand grains. This specific rounded shape is the result of mechanical weathering in a high-energy water environment like a river or beach.
Field identification & locations
Identify in the field by its gritty texture (feels like sandpaper) and its ability to leave a light streak if rubbed on a harder surface. This specimen is well-rounded, indicating significant travel from its source rock.
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