sedimentary
Glauconitic Sandstone (or Greenstone)
Glauconitic Sandstone with Quartz
Hardness: 6-7 (if quartz-rich); Color: Pale to olive green, white inclusions; Luster: Dull to earthy; Texture: Fine-grained to sandy; Cleavage: None (conchoidal fracture on quartz parts)
- Hardness
- 6-7 (if quartz-rich)
- Color
- Pale to olive green, white inclusions
- Luster
- Dull to earthy
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Physical properties
Hardness: 6-7 (if quartz-rich); Color: Pale to olive green, white inclusions; Luster: Dull to earthy; Texture: Fine-grained to sandy; Cleavage: None (conchoidal fracture on quartz parts)
Formation & geological history
Formed in marine environments through the alteration of mica and other minerals. This specimen appears to be a water-worn beach cobble from a coastal sedimentary formation.
Uses & applications
Primarily of interest to collectors or geologists; used as a soil amendment (greensand) or occasionally as building stone if found in large deposits.
Geological facts
The green color is typically caused by the mineral glauconite, an iron-potassium silicate that forms in shallow marine waters with slow sedimentation rates.
Field identification & locations
Identify by its distinctive sea-green patches against a lighter matrix and its rounded, water-worn beach context. Common in coastal areas with eroding cliffs containing sedimentary strata.
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