Fluorine-bearing minerals such as chondrodite, norbergite, clintonite, chlorite and F-rich mica in the Los Santos dolomite marbles indicate that contact metamorphism was accompanied by F metasomatism. The low HF concentration of 10-2,46 to 10-3,03 mol/dm3 estimated using experimentally calibrated phlogopite and biotite fluorimeters, is similar to that calculated in other marbles and skarns related to magmatic or hydrothermal fluids equilibrated with a granite rock