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(Mg,Fe,Al)3(Si,Al)2O5(OH)4 Green mineral of the chlorite group, occurring in monoclinic crystals, in folia or scales, or massive.



a mineral of the chlorite group; one of the layered aluminosilicates.

The approximate chemical composition of chlinochlore is

(Mg, Fe)4.75 Al,1.25 [Al,1.25 Si2.75 O10] (OH)8

The ratios of magnesium to aluminum and aluminum to silicon vary considerably, although clinochlore is primarily a magnesium-aluminum chlorite. The low-iron variety of clinochlore is known as leichtenbergite (colorless). Clinochlore containing admixtures of chromium is called kotschubeite (pinkish-violet).

Clinochlore crystallizes in the monoclinic system, forming small pseudohexagonal plumose crystals with good cleavage. Most often, clinochlore forms microplumose aggregates. Its color ranges from dark gray-green to light olive-green. Clinochlore is transparent in the form of thin laminae. Its hardness on the mineralogical scale is 2–2.5; its density varies between 2,610 and 2,780 kg per cu m. It is a rock-forming mineral in chlorite shales and occurs in other metamorphic rocks as well (appearing as a result of changes in pyroxenes, amphiboles, garnets, ferromagnesian mica). Clinochlore also exists in contact-meta-somatic rocks, such as skarns, and in modified secondary rocks in hydrothermal lodes. Clinochlore is very widely distributed in nature.


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Results of X-ray diffraction analysis of 52 stratified samples collected between 58-18 m indicated a mineralogical composition consisting mostly of quartz, muscovite, albite, clinochlore, calcite, and orthoclase (details in Giudice 2005; Dickinson 2008).
According to the XRD analyses, a Patan clay sample contains mainly muscovite and quartz phases, while a Thimi clay sample contains muscovite, quartz, albite and clinochlore phases.