
sedimentary
Glauconitic Sandstone
Glauconitic arenite (contains (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
AI-generated identification · may be incorrectHardness: 2-3 (Mohs scale for the glauconite grains); Color: Dull olive-green to bluish-green on host matrix; Luster: Earthy to dull; Crystal structure: Monoclinic (micaceous grains); Cleavage: Perfect basal (though often appears as shapeless masses/pellets).
- Hardness
- 2-3 (Mohs scale for the glauconite grains)
- Color
- Dull olive-green to bluish-green on host matrix
- Luster
- Earthy to dull
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Physical properties
Hardness: 2-3 (Mohs scale for the glauconite grains); Color: Dull olive-green to bluish-green on host matrix; Luster: Earthy to dull; Crystal structure: Monoclinic (micaceous grains); Cleavage: Perfect basal (though often appears as shapeless masses/pellets).
Formation & geological history
Formed in marine environments through the chemical alteration of organic matter or mica in shallow, slow-depositing waters. Typically found in Cretaceous or Cenozoic era strata.
Uses & applications
Used primarily as a soil conditioner and source of potassium (greensand), water softener, and historically as a green pigment for artists.
Geological facts
Often called 'Greensand,' it is an indicator of a slow rate of sedimentation in a marine setting. It can be found in the famous 'Peach Springs' Member or Cretaceous outcrops across North America.
Field identification & locations
Identify by its distinctive dull green hue and crumbly, sandy texture on the surface of a darker host rock. Look for it in coastal plains or marine-origin sedimentary belts. Collectors should keep specimens dry to prevent crumbling.
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