Changes in bornite (Cu ₅ FeS ₄ ) after heating in air: Mössbauer effect study

The phase transitions and structural behaviour in natural bornite sample were investigated after heat treatment in air in a temperature range of (180÷500) ^◦ C using high-resolution Faraday, X-ray diffraction and ⁵ 7Fe Mössbauer spectroscopy studies. X-ray diffraction and the Mössbauer spectroscopy results show that polymorph phases can exist only at high temperatures, and at a temperature of 220 ^◦ C a process of decomposition of bornite structure starts. Hematite is a main Fe-bearing phase and Cu is located mainly in cooper oxides present in the sample after annealing at 500 ^◦ C.