Clintonite - Encyclopedia

    Class : Silicates
    Subclass : Phyllosilicates
    Crystal system : Monoclinic
    Chemistry : CaMg₂Al₄SiO₁₀(OH)₂
    Rarity : Uncommon

Clintonite is a fairly rare mineral from the mica group. It is with margarite, one of the "hard" micas, in which calcium is the main interfoliar cation. This property results in harder and more brittle cleavage blades than in conventional micas, such as muscovite or biotite. Clintonite is a calcium equivalent of phlogopite, although with a lower Si/Al ratio. It was named in honor of the American politician De Witt Clinton. It is a metamorphic mica which is found in aluminous rocks of low to medium degree of metamorphism (chloritoschists, mica-schists, etc...), as well as in metasomatized limestones and in certain siliceous skarns, associated with talc, vesuvianite, grossular, and generally to calcium minerals. It is variable in color, from bottle green to grass green or pale yellow-orange to red-brown. It forms pseudohexagonal tabular crystals, often with complex twins, sometimes simulating an octahedron, it also occurs in encrustations or aggregates.

Main photo : Clintonite from Green Monster Mountain, Alaska, USA © John Rakovan

Presence of complex twins.

No fake identified for this mineral species.