sedimentary

Glauconitic Sandstone

Glauconitic arenite (contains (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)

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).

Hardness: 2-3 (Mohs scale for the glauconite grains)
Color: Dull olive-green to bluish-green on host matrix
Luster: Earthy to dull

Identified March 24, 2026More sedimentary →

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Physical properties

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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