Turkish Journal of Earth Sciences




Lens-shaped talc deposits related to Mesozoic gabbroic rocks are exposed in an area of 2 km^2, about 80 km northwest of Afyonkarahisar (western Anatolia). Different alteration zones in talc deposits were determined depending on differences related to the texture and color of the host rock. In order to determine mineralogical, geochemical, and physicochemical features of the Emirdağ talc deposits, X-ray diffractometer, scanning electron microscope (SEM), FT-IR and Mössbauer spectroscopy, differential thermogravimetric analyses, BET-specific surface area, color, water soluble substance, acid-soluble carbonate, and acid-soluble iron tests were performed on the samples collected from different alteration zones in the lateral direction. Four groups of mineral paragenesis were determined: i) talc and chlorite-bearing actinolite (E1), ii) actinolite-rich talc (E-2), iii) chlorite and calcite-bearing talc (E-3), and iv) pure talc (E-4). Talc, actinolite, and chlorite are dominant. SEM analyses show that fine shreds, like microcrystalline talc crystals, are associated mainly with actinolite and chlorite, and actinolites are mainly transformed into chlorite and talc. Ni and Cr contents of the Emirdağ talcs are consistent with the composition of the talc deposits formed in relation to ultramafic rocks. Energy dispersive X-ray spectrometry, chemical analysis, and Mössbauer spectroscopy results show that iron in the Emirdağ samples was mainly derived from talc minerals and this iron occurs as Fe^{+2} in the crystal lattice structure of talc. Because removal of iron from Emirdağ talc seems difficult during mineral processing techniques, the Emirdağ talc can be used in its crude state in the cosmetic, paint, and paper industries as a secondary raw material.

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