metamorphic
Red Quartzite River Pebble
Quartzite (SiO2 with iron oxide inclusions)
Hardness: 7 on Mohs scale; Color: Reddish-brown to tan; Luster: Dull to vitreous; Crystal Structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6 - 2.8
- Hardness
- 7 on Mohs scale
- Color
- Reddish-brown to tan
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-brown to tan; Luster: Dull to vitreous; Crystal Structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6 - 2.8
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure, the sand grains recrystallize into a dense, interlocking matrix. This specific specimen has been further shaped by fluvial erosion in a river or beach environment, resulting in a smooth, rounded 'pebble' texture.
Uses & applications
Used primarily in landscaping, construction as crushed stone or ballast, and as a durable material for pathways. Polished versions are used in home decor or as worry stones.
Geological facts
Quartzite is so tough that it often survives trillions of years of weathering, outlasting many other rock types. The red coloration is typically caused by tiny amounts of hematite (iron oxide) staining the quartz grains.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its smooth, rounded egg-like shape if found in waterbeds. It is found globally in areas with ancient mountain ranges, such as the Appalachian Mountains or the Scottish Highlands.
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