Formula: CaAlMg2(SiAl3O10)(OH)2
Phyllosilicate (sheet silicate), brittle mica group
Crystal System: Monoclinic
Specific gravity: 3.0 to 3.1 measured, 3.12 calculated
Hardness: 3½ parallel to {001}, 6 perpendicular to {001}
Streak: Colourless to pale tan
Colour: Colourless, pale yellow to greenish yellow, orange to reddish brown
Common impurities: Na,K,Ti,Fe,F

Metamorphic environments

Clintonite occurs in chlorite schist with talc, and in metasomatised limestone with spinel, grossular, vesuvianite, diopside, clinopyroxene, monticellite, chondrodite, phlogopite, chlorite, quartz, calcite, dolomite and humite group minerals (Dana, HOM).


At the Solo Skarn, Ertsberg Complex, Gunung Bijih District, Carstensz Mts, New Guinea, Papua Province, Western New Guinea, Indonesia, clintonite occurs in a pit; associated minerals in the pit and nearby drill holes include calcite, dolomite, anhydrite, monticellite, forsterite, vesuvianite, and aluminium-bearing lizardite (AM 73.365-375).

At Green Monster Mountain, Prince of Wales Island, Ketchikan Mining District, Prince of Wales-Hyder Census Area, Alaska, USA, a limited number of excellent specimens of intensely green rosettes of clintonite to 1.5 cm have been found. Most have weathered free of enclosing calcite in a calcite-rich skarn (Minrec 35.5.394-395).

At Christmas Mine, Middle Pass District, Dragoon Mts, Cochise county, Arizona, USA, clintonite occurs in metamorphosed diorite (Dana).

At Crestmore, Riverside county, California, USA, large dark green clintonite crystals to 4.2 cm across have been found, included in masses of blue calcite to 20 cm long, sparingly accompanied by yellowish green vesuvianite. Both clintonite and calcite have a few streaks and surface coatings of hematite, and monticellite is another associated mineral. (Minrec 35.4.328-330, Dana).

At the type locality, Amity, Town of Warwick, Orange county, New York, USA, clintonite occurs in high temperature marble, associated with spinel, pyrrhotite, phlogopite, graphite, chondrodite and calcite (Mindat).

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