sedimentary
Siltstone or Sandstone Pebble
Lithic Arenite / Quartzose Siltstone
Hardness: 6-7 (Mohs scale); Color: uniform grey; Luster: dull; Texture: fine-grained, smooth, well-rounded due to erosion; Specific Gravity: 2.6-2.7
- Hardness
- 6-7 (Mohs scale)
- Color
- uniform grey
- Luster
- dull
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Physical properties
Hardness: 6-7 (Mohs scale); Color: uniform grey; Luster: dull; Texture: fine-grained, smooth, well-rounded due to erosion; Specific Gravity: 2.6-2.7
Formation & geological history
Formed by the deposition and lithification of fine-grained silicate minerals. This specific specimen has been shaped and smoothed through fluvial or coastal abrasion over long periods of time.
Uses & applications
Commonly used as decorative landscaping stones, river rocks for walkways, and in construction as aggregate. Smooth specimens are often used in spa massage therapy.
Geological facts
The smooth, oval shape indicates a long journey in water, where constant tumbling against other rocks ground away its rough edges. The grey color often indicates high quartz and feldspar content.
Field identification & locations
Identify in the field by its smooth, matte texture and lack of visible crystals. Commonly found in riverbeds and on coastal beaches.
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