Chlorite group

As chlorite (short chlorites from Greek chloros = green) is a group of layer silicate minerals from the mineral class of silicates and Germanates referred to the general, chemical composition (Fe, Mg, Al, Zn ) 6 ( Si, Al) 4O10 ( OH) 8.

In brackets atoms can be represented in any combination, but always stand in the same relation to the other groups of atoms. Chlorite has a relatively low hardness of 2 to 3, a green, sometimes yellow-brown color and a white stroke color.

Etymology and history

The magnesium-rich chlorite group of talc was first scientifically described in 1862 by Alfred Des Cloizeaux and the mineral clinochlore by William Phipps Blake in 1851.

In special cases Chloritminerale are rock forming minerals. The first scientific description of the Chloritgesteine ​​dates from the year 1879 by Alexander Alexandrovich Inostranzew ( studies of the metamorphosed rocks in the General Government. Olonetz ).

Individual minerals and varieties

The Eisenendglied the chlorites is denoted by chamosite, the Magnesiumendglied with clinochlore, the Manganendglied with Pennantit that Nick misery link with Nimit and Zinkendglied with Bailey chlorine.

Minerals of the group are as follows:

  • Bailey chlorine
  • Borocookeit
  • Chamosite Rhipidolith ( magnesium- rich )
  • Thuringite (iron- rich )
  • Delessite (iron- rich )
  • Rhipidolith (iron- rich )

Education and Locations

Chlorite occurs both massive and fine- grained; Also, crystals occur, which are often combined in scaly aggregates. The mineral is found in igneous rocks, weakly metamorphosed rocks, the chlorite and Chloritfelsgesteinen and argillaceous sedimentary rocks. A well-known example is the Marx Green marble from the Franconian Forest.

Furthermore, members of the chlorite group, in addition to kaolinite, finely accompanying minerals of bauxite deposits. The sudoite and Donbassite occurs in the French bauxite deposits of the Pyrenees, from Gasconade County in the U.S. state of Missouri and in some deposits on Hungary. Further more Chloritminerale as clinochlore and chamosite are found in other bauxite deposits.


Chlorites are similar in structure and composition of the micas.

Use as raw material

As early as the third millennium BC chlorites has been processed and decorated Chloritgefäße prepared therefrom. A center for these early historical production was Tepe Yahya in Iran today, where chlorite was plenty to be found.

Chamosite and their training variant thuringite that occur in iron-rich sediments are mined as iron ore.