sedimentary
Glauconite (Greensand Articulated Sandstone)
Glauconite ((K, Na)(Fe, Al, Mg)2(Si, Al)4O10(OH)2)
Hardness: 2.0; Color: Olive green, black-green, or brownish if weathered; Luster: Dull to earthy; Crystal structure: Monoclinic; Cleavage: Perfect; Specific gravity: 2.4-2.95
- Hardness
- 2
- Color
- Olive green, black-green, or brownish if weathered
- Luster
- Dull to earthy
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Physical properties
Hardness: 2.0; Color: Olive green, black-green, or brownish if weathered; Luster: Dull to earthy; Crystal structure: Monoclinic; Cleavage: Perfect; Specific gravity: 2.4-2.95
Formation & geological history
Formed in marine environments through the alteration of minerals or organic matter on the seafloor, typically in shallow shelf waters with slow sedimentation rates. Often Cretaceous to Tertiary in age.
Uses & applications
Used as a water softener, a slow-release fertilizer for potassium, and historically as a green pigment in paints.
Geological facts
Known as greensand, it is often used as a geological marker to indicate ancient marine conditions and slow deposition environments.
Field identification & locations
Identify by its characteristic dark green to black-green color and sandy/crumbly texture. Commonly found in coastal plain sedimentary deposits (e.g., New Jersey, USA).
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