sedimentary

Glauconite (Greensand)

(K, Na)(Fe3⁰, Al, Mg)₂(Si, Al)₄O₁₀(OH)₂

AI-generated identification · may be incorrect

Hardness: 2.0; Color: dull green to bluish-green; Luster: earthy to pearly; Crystal structure: monoclinic; Cleavage: perfect (micaceous); Specific Gravity: 2.4 - 2.95.

Hardness: 2
Color: dull green to bluish-green
Luster: earthy to pearly

Identified May 24, 2026More sedimentary →

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Physical properties

Hardness: 2.0; Color: dull green to bluish-green; Luster: earthy to pearly; Crystal structure: monoclinic; Cleavage: perfect (micaceous); Specific Gravity: 2.4 - 2.95.

Formation & geological history

Glauconite forms in marine environments through the alteration of minerals (like mica) or organic matter in shallow continental shelf waters. It typically dates from the Cambrian period to the present.

Uses & applications

Used primarily as a soil conditioner and organic fertilizer due to its potassium content. It was historically used as a pigment (green earth) in paintings and is used in water softening systems.

Geological facts

Glauconite is a 'facies indicator,' meaning its presence tells geologists that the area was once a shallow, slow-sedimenting marine environment. It is often found as small rounded pellets.

Field identification & locations

Identify by its distinctive dull green color and crumbly texture. Search in coastal plains or sedimentary rock outcrops, notably in the New Jersey coastal plain or certain Cretaceous formations.