sedimentary

Glauconitic Sandstone

Glauconitic Sandstone (Quartz with Glauconite)

Hardness 6-7 (quartz matrix), dull to earthy luster, fine to medium grain size, distinctive greenish-gray to blue-green tint due to iron-rich glauconite mixed with tan/beige silica sand, clastic texture with faint bedding layers.

Identified July 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow, oxygen-poor marine environments through the slow accumulation and diagenesis of quartz grains along with iron-potassium phyllosilicate minerals (glauconite). Common in Cretaceous and Paleogene sedimentary strata.

Uses & applications

Used historically as building stone, architectural flagstone, source of green pigment, soil conditioner (greensand), and geological study specimens.

Geological facts

Glauconite is often referred to as 'greensand' and indicates slow rates of accumulation in shallow sea environments. The greenish tinge is created by hydrous iron-rich potassium silicate minerals within the sandstone matrix.

Field identification & locations

Identified in the field by its sandy, abrasive texture combined with characteristic greenish-blue or sage-green patches amidst tan or gray sedimentary layers. Commonly found in coastal sedimentary exposures, river beds, and quarry outcrops worldwide.

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Sandstone or Siltstone

Arenite (if sandstone)

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Sedimentary Sandstone

Arenite (Sedimentary Rock)

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Fossiliferous Concretion

Septarian Concretion containing Brachiopods/Crinoids

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Shale

Shale (clastic sedimentary rock)

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Shale

Argillaceous sedimentary rock

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Mudstone

Argillite / Siliciclastic sedimentary rock

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