sedimentary
Glauconitic Sandstone
Glauconitic Sandstone (Greensand)
Hardness: 6-7 (individual grains); Color: Dark grey to dull green with black speckles; Luster: Dull/Earthy; Structure: Clastic, fine-grained; Specific Gravity: 2.4-2.8
- Hardness
- 6-7 (individual grains)
- Color
- Dark grey to dull green with black speckles
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (individual grains); Color: Dark grey to dull green with black speckles; Luster: Dull/Earthy; Structure: Clastic, fine-grained; Specific Gravity: 2.4-2.8
Formation & geological history
Formed in marine environments through the accumulation of quartz grains and the mineral glauconite, typically in shallow shelf areas. Often dates from the Cretaceous to Cenozoic periods.
Uses & applications
Historically used as a soil conditioner (source of potassium), for water filtration, and occasionally as a low-grade construction material.
Geological facts
The dark speckles often visible are glauconite pellets. Large deposits in North America are found in the Atlantic Coastal Plain, particularly New Jersey.
Field identification & locations
Identified by its sandy texture and greenish-grey hue. It often feels slightly rough to the touch and may contain microfossils or organic debris characteristic of old sea beds.
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