Static magnetic susceptibilities have been measured on an α-quartz single crystal that had been irradiated with fast neutrons. Above 65 K, the radiation-induced paramagnetism obeys the Curie law, indicating the presence of non-interacting centres. The low-temperature measurements result in a field-dependent susceptibility comparable to the effect of the Brillouin saturation of non-interfacing centres. The average moment per centre, however, is higher than the one due to the spin only of single unpaired electrons, pointing to ferromagnetically coupled electron pairs. When the calculated susceptibility values, as obtained from the derived moments and concentrations using the Brillouin theory, are subtracted from the measured data, then the differences behave—over the whole temperature range—as the susceptibility of antiferromagnetically coupled electrons. On the same sample also, low-temperature 20.9 GHz ESR measurements have been carried out. The major resonance line is attributed to theE’ centre. The general behaviour clearly corroborates the presence of interactions; the effect does not show anisotropy.