mineral
Glauconite
(K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2
Hardness: 2 Mohs; Color: Dull green, olive green, or blue-green; Luster: Dull to pearly; Crystal structure: Monoclinic; Cleavage: Perfect; Specific gravity: 2.4 - 2.85
- Hardness
- 2 Mohs
- Color
- Dull green, olive green, or blue-green
- Luster
- Dull to pearly
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Physical properties
Hardness: 2 Mohs; Color: Dull green, olive green, or blue-green; Luster: Dull to pearly; Crystal structure: Monoclinic; Cleavage: Perfect; Specific gravity: 2.4 - 2.85
Formation & geological history
Formed authigenically in shallow marine environments under anaerobic conditions, typically found in sedimentary deposits like 'greensands' during the Cretaceous and Tertiary periods.
Uses & applications
Used as a water softener (zeolite-like properties), a soil conditioner/fertilizer due to potassium content, and a green pigment in art.
Geological facts
Glauconite is the primary constituent of 'greensand' and is often used by geologists as an indicator of sea level change and depositional environments.
Field identification & locations
Identify by its characteristic dull green earthy appearance and tendency to crumble into small pellets or granules. Commonly found in coastal sedimentary outcrops and drill cores.
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