sedimentary

Glauconitic Sandstone (or Greensand)

Glauconitic Siliciclastic Rock (Containing (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

AI-generated identification · may be incorrect

Hardness: 2-3 (for the glauconite grains) to 6-7 (if silica-cemented); Color: Dull olive-green to grayish-green; Luster: Earthy to dull; Crystal structure: Monoclinic (micaceous grains); Cleavage: Perfect basal (on micaceous grains); Specific gravity: 2.4-2.85.

Hardness: 2-3 (for the glauconite grains) to 6-7 (if silica-cemented)
Color: Dull olive-green to grayish-green
Luster: Earthy to dull

Identified March 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in marine environments as a result of chemical weathering and alteration of micas or volcanic glass in fecal pellets or organic remains. Typically found in shelf-depth marine waters. These deposits are often found in strata ranging from the Cambrian to the present, notably prevalent in Cretaceous and Tertiary formations.

Uses & applications

Used primarily as a soil conditioner and natural fertilizer due to its potassium content. Historically used as a pigment ('green earth') in painting, and occasionally as a water softener due to its ion-exchange properties.

Geological facts

Commonly known as 'Greensand,' this material was widely used in 19th-century agriculture and is a vital indicator of slow sedimentation rates in ancient marine environments. Large deposits in New Jersey are world-famous for their paleontological findings.

Field identification & locations

Identify by its characteristic dull green color and sandy, granular texture. It often leaves a green streak when crushed. Found commonly in coastal plains, such as the eastern US (New Jersey, Delaware) and parts of the UK. Collectors should look for associated marine fossils like shark teeth or oyster shells.