sedimentary
Glauconitic Sandstone
Glauconitic Quartz Arenite
Hardness: 2-3 (glauconite) to 7 (quartz matrix), Color: Dull green, blue-green, or olive-drab, Luster: Earthy to pearly, Structure: Granular/clastic, Specific Gravity: 2.4-2.85
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Physical properties
Hardness: 2-3 (glauconite) to 7 (quartz matrix), Color: Dull green, blue-green, or olive-drab, Luster: Earthy to pearly, Structure: Granular/clastic, Specific Gravity: 2.4-2.85
Formation & geological history
Formed in marine continental shelf environments under reducing conditions, typically through the alteration of fecal pellets or silicate minerals. Most deposits date from the Cambrian to the Cenozoic eras.
Uses & applications
Used primarily as a slow-release potassium fertilizer (greensand), a water softener due to its ion-exchange properties, and occasionally as a pigment or soil conditioner.
Geological facts
Glauconite is often referred to as 'greensand' and its presence is a definitive indicator of a marine depositional environment. It requires very slow rates of sedimentation to form.
Field identification & locations
Identify in the field by its characteristic 'dirty' green color and crumbly texture. It is commonly found in coastal plain sedimentary sequences such as those in New Jersey, USA, or the Isle of Wight.
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