sedimentary
Glauconitic Sandstone
Glauconite-bearing Arenite (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2
Hardness: 2-3 (glauconite) to 7 (quartz matrix), Color: Dull olive-green to blackish-green, Luster: Earthy to dull, Crystal Structure: Monoclinic (micaceous), Specific Gravity: 2.4 - 2.8
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Physical properties
Hardness: 2-3 (glauconite) to 7 (quartz matrix), Color: Dull olive-green to blackish-green, Luster: Earthy to dull, Crystal Structure: Monoclinic (micaceous), Specific Gravity: 2.4 - 2.8
Formation & geological history
Formed in marine continental shelf environments through the slow accumulation of fecal pellets and organic debris in reducing conditions. Typically indicates a slow rate of sedimentation during the Cretaceous or Cenozoic eras.
Uses & applications
Used primarily as a soil conditioner (Greensand) due to its potassium content, in water filtration, and historically as a green pigment for paints.
Geological facts
The green color is derived from iron within the glauconite mineral. It is often referred to by gardeners as 'Greensand' and is valued for its slow-release fertilizing properties.
Field identification & locations
Identify by its distinctive olive-green color and crumbly texture. It is commonly found in coastal plain sedimentary deposits, such as those in New Jersey, USA, or the South Downs in England.
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