Chloritization of smectite, usually with corrensite as a transition phase, is a basic process of a change for 2:1 trioctahedral clay minerals (Ca and Mg smectite).
These features likely reflect hydrothermal alteration (e.g., silicification, sericitization, and
chloritization), as indicated by petrographic observation, and are not the result of magmatic fractionation.
Epidotization and
chloritization can be seen in fractures.
In active orogenic belt hydrothermal fluids alter feldspar and plagioclase into extremely fine grained quartz and mica in the form of muscovite or sericite by sericitization while the same fluids alter biotite and garnets into chlorite by
chloritization. Similarly the intergrowth reaction between plagioclase and k-feldspar produces fine blebs of quartz by myrmekitization which is extremely susceptible to ASR.
and Amouric, M.: 1984, Biotite
chloritization by interlayer brucitization as seen by HRTEM.
the last Hercynian phase of folding, the overthrusting of the basement by the cover rocks with lamination of the dolomite and country rock, the percolation of magnesian hydrothermal fluids and
chloritization of the aluminosilicate facies (mica schist, aplite, pegmatite), and finally metasomatic "talcification" of the dolomite and siliceous rocks.
This displacement is accompanied by hydrothermal alteration of granodiorite porphyries (
chloritization and albitization).
Silicification, sericitisation and
chloritization are the principal alteration types observed in the mine.