Sedimentary and Metamorphic
Sandstone, Quartzite, and River Pebbles
Silicon Dioxide (SiO2) based Sedimentary/Metamorphic structures
Hardness: 6-7 Mohs; Colors: Tan, grey, reddish-brown; Luster: Dull/Earthy to slightly Waxy; Structure: Clastic or Granoblastic; Cleavage: None/Conchoidal fracture.
- Hardness
- 6-7 Mohs
- Luster
- Dull/Earthy to slightly Waxy
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Physical properties
Hardness: 6-7 Mohs; Colors: Tan, grey, reddish-brown; Luster: Dull/Earthy to slightly Waxy; Structure: Clastic or Granoblastic; Cleavage: None/Conchoidal fracture.
Formation & geological history
Formed through the accumulation of sand grains (sandstone) or the heat/pressure metamorphization of those sands (quartzite). The rounded shapes indicate erosion in high-energy water environments like rivers or beaches.
Uses & applications
Construction aggregate, decorative landscaping, glass manufacturing (if high purity silica), and historical use as building stone or sharpening tools.
Geological facts
The stack displays stones in various stages of the rock cycle: the base is a block of rough sandstone, the middle red stone is likely arkose or oxidized sandstone, and the top rounded grey stones are river-worn clasts.
Field identification & locations
Identify in the field by their gritty texture (sandstones) or smooth, water-worn surfaces (river stones). Commonly found in dry riverbeds, alpine glacial deposits, and coastal regions worldwide.
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Mineral