Clinochlore - Encyclopedia

    Class : Silicates
    Subclass : Phyllosilicates
    Crystal system : Monoclinic
    Chemistry : Mg5Al(Si3Al)O10(OH)8
    Rarity : Very rare

Clinochlore is one of the four main species of the group of chlorites, common phyllosilicates of magnesium, iron and aluminium. It is the magnesian term of the group, which constitutes a continuous series with the ferriferous term : chamosite. Its name comes from the Greek klino (to lean) and khlôros (green), due to its inclined optical axes and its green color. Clinochlore is the most frequent chlorite, common in low gradient metamorphic rocks (chlorite schists, zeolite facies), as well as in altered magmatic rocks (basalts, spilites, gabbros...), serpentinites, certainmarbles, and aureoles of alteration around hydrothermal deposits (so-called propylitic alteration). In these alteration contexts, clinochlore comes from the transformation of ferromagnesian minerals (biotite, amphibole, pyroxene). Like other chlorites, clinochlore occurs as squat, pseudohexagonal lamellar crystals, flattened on {001}, sometimes taking the appearance of barrels or acute rhombohedra with horizontally striated faces. Sector twins are not uncommon. It also occurs in leafy, vermicular, or scaly aggregates and in compact masses, finely crystalline to cryptocrystalline. The color is usually dark green to greenish black, exceptionally colorless, yellow or purplish red (kämmererite). Its varieties are numerous : pennine, ripidolite (finely crystallized variety), sheridanite, brunsvigite, all transition terms with ferriferous chamosite, and kämmerite.
Massive it is used in ornamentation under the trade name of seraphinite. Clinochlore, and more generally chlorites, have only a very marginal industrial use. Chlorite powder is sometimes used in decoration to enhance the shine of wallpaper.

72.80 ct seraphinite cabochon from Russia
33.00 ct seraphinite cabochon from Russia
23.49 ct seraphinite cabochon from Russia
43.22 ct seraphinite cabochon from Russia

Clinochlore in the World

Pure clinochlore crystals are rarely centimetric, the most beautiful specimens of clinochlore come from Italian Piedmont : Pian Della Mussa, where the crystals accompany orange grossular and gemmy diopside (photo on the right), and Traversella. Beautiful centimetric lamellar crystals were extracted from the Tilly Foster mine (New York) and the Jeffrey mine (Quebec, Canada). Exceptional dark green crystals exceeding 50 cm of the pennine variety are known from moraines near Mount Rimpfishwänd (Zermatt, Switzerland). This variety is also known in magnificent crystals in different parts of the Urals (Russia) and Val Malenco (Italy). The extremely rare chrome variety, kämmerite, provides crystals up to 2 cm in the Kop Krom mine, near Uruzum (Turkey).

Clinochlore in France

Clinochlor is present in good specimens in the alpine clefts of St-Christophe-en-Oisans (Isère) as well as at the Canari Mine (Corsica), It is found in aesthetic microcrystals in the talc quarries of Trimouns (Ariège).


Sectorial twinning in common but impossible to identify with the naked eye.

Fakes and treatments

No fake inventories for this mineral species.

Hardness : 2 to 2.5
Density : 2.6
Fracture : Scaly
Trace : White to green

TP : Translucent to transparent
RI : 1.571 to 1.599
Birefringence : 0.005 to 0.011
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : None

Solubility : Sulfuric acid

Magnetism : None
Radioactivity : None


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