Mineral Species: Clinochlore var. Pennine

Chemical Formula: (Mg,Fe++)5Al(Si3Al)O10(OH)8

Chemical Name: Magnesium Iron Aluminium Silicate Hydroxide

Mineral Class: Phyllosilicate

Mineral Notes: Clinochlore is one of the more common members of the Chlorite Group. These minerals are all difficult to differentiate by ordinary means and often the general mineral name Chlorite is given to specimens that lack distinguishing characterics. Clinochlore forms from the metamorphic and hydrothermal alteration of other iron and magnesium silicates. Clinochlore gets its name from the Greek words for inclined and green since its structure is monoclinic and its common colour is green. Clinochlore forms a series with Chamosite. Chamosite is the iron rich equivalent of Clinochlore. Their properties are only slightly different with Chamosite being darker and less transparent than Cinochlore. Pennine is a variety of Clinochlore that forms pseudo-trigonal crystals.

Description: Spherical, crystalline aggregates of Pennine on matrix. Close inspection shows that each cluster is composed of thin, bladed crystals. The mineral has a striking metallic luster and steel-grey colour. An excellent example of this rare species.

Location: Lengenbach, Binntal, Wallis, Switzerland