mineral

Celadonite in Basalt (Green Earth)

Celadonite (K(Mg,Fe2+)(Fe3+,Al)Si4O10(OH)2)

AI-generated identification · may be incorrect

Hardness: 2; Color: Blue-green to apple-green; Luster: Dull to pearly; Crystal structure: Monoclinic; Cleavage: Perfect mica-like cleavage; Specific gravity: 2.7-3.0

Hardness: 2
Color: Blue-green to apple-green
Luster: Dull to pearly

Identified April 5, 2026More mineral →

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Physical properties

Hardness: 2; Color: Blue-green to apple-green; Luster: Dull to pearly; Crystal structure: Monoclinic; Cleavage: Perfect mica-like cleavage; Specific gravity: 2.7-3.0

Formation & geological history

Formed as an alteration mineral in the vesicles (gas bubbles) or cracks of volcanic rocks like basalt through low-grade hydrothermal metamorphism.

Uses & applications

Historically used as a stable green pigment ('Terra Verte' or Green Earth) in paintings and icons; also collected by mineral enthusiasts as an inclusion or coating.

Geological facts

It belongs to the mica group and is chemically very similar to glauconite, but it is primarily found in volcanic environments rather than marine sedimentary environments.

Field identification & locations

Identify by its distinctive soft, earthy green appearance often found lining the cavities of dark volcanic rocks. It feels slightly greasy and is soft enough to scratch with a fingernail.