mineral
Glauconite
Glauconite (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2
AI-generated identification · may be incorrectHardness: 2.0; Color: Blue-green, olive-green; Luster: Pearly to dull; Crystal structure: Monoclinic; Cleavage: Perfect mica-like; Specific Gravity: 2.4-2.95
- Hardness
- 2
- Color
- Blue-green, olive-green
- Luster
- Pearly to dull
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Physical properties
Hardness: 2.0; Color: Blue-green, olive-green; Luster: Pearly to dull; Crystal structure: Monoclinic; Cleavage: Perfect mica-like; Specific Gravity: 2.4-2.95
Formation & geological history
Formed in marine continental shelf environments through the slow diagenetic alteration of organic matter, mica, or clay minerals in reducing conditions. Most common in sedimentary rocks from the Cambrian to Holocene.
Uses & applications
Used primarily as a soil conditioner and source of potassium/iron in organic fertilizers. Historically used as a pigment (green earth) and for water softening via ion exchange.
Geological facts
Glauconite is often found in 'greensands'. It is a key indicator of slow sedimentation rates in marine environments and is used by geologists for radioactive dating of sedimentary sequences.
Field identification & locations
Identify in the field by its distinctive dull green rounded pellets (granules) and its tendency to crumble into a green powder when crushed. Commonly found in coastal sedimentary deposits.
