CLINOZOISITE

    Class : Silicates
    Subclass : Sorosilicates
    Crystal system : Monoclinic
    Chemistry : Ca2Al3(SiO4)3(OH)
    Rarity : Uncommon

Clinozoisite belongs to the epidote group. It is a dimorph of zoisite which is found in the same deposits as epidote : low to medium grade metamorphic rocks, and calcic rocks subject to contact metamorphism. Its name is linked to its monoclinic structure and its chemical relationship with zoisite. Clinozoisite forms elongated to acicular prismatic crystals, with deeply longitudinally striated prismatic faces, often grouped in radiated masses. The color is white, gray, greenish, sometimes pinkish or pistachio green, exceptionally red. The transparent varieties are cut for jewelry.

Main photo : Clinozoisite from Alchuri, Gilgit-Baltistan, Pakistan © Lopatkin Oleg

Clinozoisite from Tormiq Valley, Haramosh Mts., Roundu Dist., Gilgit-Baltistan, Pakistan
Clinozoisite from Las Superiore Quarry, Piedmont, Italy © Franco Luca Bonino
Clinozoisite from Pianasca Quarry, Piedmont, Italy © Dario Cericola
Clinozoisite from Orrkjølen, Stange, Innlandet, Norway © OT. Ljøstad

Clinozoisite in the World

The most beautiful crystals come from the alpine clefts of Tormiq Valley and Alchuri (Pakistan) and measure up to more than 10 cm. Beautiful crystals come from Goslarwand, near Prägraten (Austria) but also from Volonandrongo (Madagascar) where the crystals are centimetric in two colors : green and pink. The Norwegian deposits of Orrkjølen and Terningmoen produced millimetric crystals but of a very beautiful red color.

Clinozoisite in France

In France, we find clinozoisite at Minerbio, near Canari (Haute-Corse) in pale green crystals up to 2 cm. Submillimeter pink crystals are described at Petches (Ariège)

Twinning

A lamellar twin is known on {100}.

Fakes and treatments

No fake identified for this mineral species.


Hardness : 7
Density : 3.3 to 3.4
Fracture : Irregular
Streak : Gray-white

TP : Translucent to transparent
RI : 1.706 to 1.735
Birefringence : 0.006 to 0.011
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : None

Solubility : -


Magnetism : Paramagnetic
Radioactivity : None