sedimentary

Glauconitic Sandstone

Glauconitic Sandstone (contains (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

AI-generated identification · may be incorrect

Hardness: 2-3 (glauconite) to 7 (quartz matrix); Color: Dull olive green to blue-green; Luster: Earthy to dull; Crystal structure: Monoclinic (microcrystalline); Specific gravity: 2.4-2.8

Hardness: 2-3 (glauconite) to 7 (quartz matrix)
Color: Dull olive green to blue-green
Luster: Earthy to dull

Identified March 28, 2026More sedimentary →

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Physical properties

Hardness: 2-3 (glauconite) to 7 (quartz matrix); Color: Dull olive green to blue-green; Luster: Earthy to dull; Crystal structure: Monoclinic (microcrystalline); Specific gravity: 2.4-2.8

Formation & geological history

Formed in marine continental shelf environments through the chemical alteration of organic matter or mica in shallow water. Typically dates from the Cambrian to the Cenezoic eras.

Uses & applications

Used historically as a soil conditioner (greensand marl) due to potassium content, as a water softener, and occasionally as a green pigment for paints.

Geological facts

Glauconite is an 'indictor mineral' for marine environments; its presence almost always proves the rock was formed in seawater. It is the primary component of 'greensand' deposits.

Field identification & locations

Identify by its characteristic dull 'pea' green color and crumbly texture. Frequently found in the Atlantic Coastal Plain of the USA (especially New Jersey) and parts of Western Europe. Collectors look for high-concentration green grains.