sedimentary

Glauconite (Glauconitic Sandstone)

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

AI-generated identification · may be incorrect

Hardness: 2-3 (as a mineral, but can vary in rock form); Color: dull green to bluish-green; Luster: dull to earthy; Crystal structure: Monoclinic; Specific gravity: 2.4-2.9.

Hardness: 2-3 (as a mineral, but can vary in rock form)
Color: dull green to bluish-green
Luster: dull to earthy

Identified April 2, 2026More sedimentary →

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Physical properties

Hardness: 2-3 (as a mineral, but can vary in rock form); Color: dull green to bluish-green; Luster: dull to earthy; Crystal structure: Monoclinic; Specific gravity: 2.4-2.9.

Formation & geological history

Formed in marine environments through the alteration of mica or fecal pellets in shallow shelves with slow sedimentation rates. Most common in Cretaceous and Tertiary age deposits.

Uses & applications

Used historically as a green pigment ('green earth'), as a water softener, and as a natural fertilizer (greensand) due to its potassium content.

Geological facts

Glauconite is a key indicator for geologists to identify paleo-marine environments and transgressive sequences (periods of rising sea levels).

Field identification & locations

Identify by its distinctive dull green color and crumbly or sandy texture. It is commonly found in coastal plain regions like New Jersey (USA) or the Isle of Wight (UK).