Magnetic susceptibilities of natural chalcopyrite from Cu ore deposits in Oman have been measured at temperatures between 77 and 450 K and magnetic field strengths between 6 and 9 kOe. The results show typical antiferromagnetism from 450 down to 190 K, where a magnetic phase transition is observed. Below the transition temperature, spontaneous magnetizations deduced from magnetic susceptibilities versus fields are extrapolated to 0 K to give a weak saturation magnetization of 0.015+/-0.001 emu g - 1 . This value could be explained by Cu moments having a paramagnetic arrangement down to 190 K and then ordering magnetically at lower temperatures.