Glauconitic Sandstone

Physical Properties

Hardness: 6-7 (Mohs scale) for grain matrix; Color: Dull green, olive, or grey-green with orange/brown iron staining; Luster: Earthy to dull; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.2-2.8

Formation & Geological History

Formed in marine shelf environments with slow sedimentation rates, typically during the Cretaceous or Paleogene periods. It results from the alteration of mica or fecal pellets in shallow sea floors.

Uses & Applications

Used primarily as a soil conditioner (Greensand) due to potassium content, a water softener, and historically as a pigment in paints.

Geological Facts

Also known as 'Greensand,' it is an excellent indicator of ancient marine environments and slow deposition. The green color comes from the iron-rich silicate mineral glauconite.

Field Identification & Locations

Identify by its characteristic dull green 'salt and pepper' appearance and crumbly to sandy texture. Common in coastal plain regions like New Jersey, USA, or the South East of England.

Identified on: 4/20/2026

Mode: Standard