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Celadonite
Chemical Formula	K(Mg,Fe2+)(Fe3+,Al)[Si4O10](OH)2
Species	Silicates
Crystal System	Monoclinic
Mohs Scale	2
Specific Gravity	3
Color	Blue-green, olive green, apple green
Luster	Dull
Refractive Index	n = 1.606 - 1.625 n = 1.630 - 1.662 n = 1.579 - 1.661
Diaphaneity	Translucent
Cleavage	Perfectperfect on
Crystal Habit：Minute micaceous scales or earthy aggregates
Geological Setting：Replaces ferromagnesian minerals in altered intermediate to mafic igneous rocks, zeolite grade metamorphic rocks, amygdaloidal fillings in basalts and andesites.

Celadonite is a mica group mineral, a phyllosilicate of potassium, iron in both oxidation states, aluminium and hydroxide with formula: K(Mg,Fe²⁺)(Fe³⁺,Al)[Si₄O₁₀](OH)₂.

It crystallizes in the monoclinic system and usually forms massive aggregates of prismatic crystallites or in dull clay masses. It is soft with a Mohs hardness of 2 and a specific gravity of 3. Typically occurs as dull gray-green to bluish green masses. It forms vesicle fillings and linings in altered basaltic lavas.

It was first described in 1847 on Mt. Baldo, near Verona, Italy. The name is from the French celadon, for sea-green.