sedimentary
Glauconite Sandstone
Glauconitic Sandstone (K(Fe,Al)2(Si,Al)4O10(OH)2)
Hardness: 2-3 (glauconite grains) to 6-7 (quartz matrix), Color: Dull olive-green to bluish-green, Luster: Earthy to dull, Structure: Granular or friable, Cleavage: Micaceous (in individual grains)
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Physical properties
Hardness: 2-3 (glauconite grains) to 6-7 (quartz matrix), Color: Dull olive-green to bluish-green, Luster: Earthy to dull, Structure: Granular or friable, Cleavage: Micaceous (in individual grains)
Formation & geological history
Formed in shallow marine shelf environments through the slow accumulation of organic debris and fecal pellets in reducing conditions. It is common in Cretaceous and Tertiary marine strata.
Uses & applications
Used as a soil conditioner (Greensand) due to its potash content, a water softener, and historically as a green pigment for artists.
Geological facts
Glauconite is an indicator of slow sedimentation rates in marine environments. It is often referred to as 'Greensand' when it occurs in unconsolidated, sandy deposits.
Field identification & locations
Identify by its distinct greenish-grey granular appearance and tendency to crumble into sand-like grains if friable. Commonly found in coastal plain sedimentary sequences.
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