sedimentary

Glauconitic Sandstone (Greensand)

Glauconite (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2

AI-generated identification · may be incorrect

Hardness: 2-3 (Mohs scale), Color: Dull green, olive green, or gray-green, Luster: Dull/Earthy, Crystal Structure: Monoclinic (micaceous), Cleavage: Perfect basal (usually appears as rounded crumbs), Specific Gravity: 2.4-2.9.

Identified February 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in marine environments slow-depositing continental shelf settings through the alteration of detrital mica or fecal pellets. It is typically found in strata from the Cambrian to the Cenozoic eras.

Uses & applications

Used primarily as a soil conditioner (Green Sand) to provide potassium and iron, as a water softener, and historically as a pigment. It is also used in filtering systems due to ion exchange properties.

Geological facts

Glauconite is an 'atypical' mineral because it forms almost exclusively in marine waters. Its presence in a rock layer is a strong indicator of a slow rate of sedimentation in a shallow sea environment.

Field identification & locations

Identify in the field by its distinct dull green color and crumbly texture. It often colors entire sandstone beds green. Found commonly in the Atlantic Coastal Plain of the USA, particularly New Jersey, and parts of the UK.