An apparatus for carrying out a quality control on industrial production lines, comprising at least two apparatuses (30, 40, 50; HZ) for the measurement of properties of a product sample of said industrial production lines, said at least two apparatuses (30, 40, 50; HZ) supplying respective measurement signals (Y1, Y2, Y3; YZ), said apparatus comprising - a processing module configured for processing said measurement signals (Y1, Y2, Y3; YZ) supplied by said at least two measurement apparatuses (30, 40, 50; HZ) and obtaining properties of said product sample, said quality control being carried out as a function of said properties of said product sample, said at least two apparatuses (30, 40, 50, HZ) for the measurement of properties of a product sample further comprising: - an x-ray fluorescence apparatus comprising an x-ray source, which emits a first x-ray beam (XB, XBC) towards said product sample in a measurement environment, and a particle detector, which is configured for receiving a second x-ray beam scattered by said product sample and for generating a first received signal supplied within the set of said respective measurement signals (Y1, Y2, Y3, YZ), said apparatus further comprises: - an optical-spectroscopy apparatus operating in a frequency band belonging to the range of optical frequencies, preferably operating in the band of the near infrared, comprising an optical-radiation source, which emits a first beam of optical radiation towards a product sample, and an optical sensor configured for receiving a second beam of radiation scattered by said product sample and for generating a second received signal supplied within the set of said respective measurement signals (Y1, Y2, Y3; YZ) and said apparatus is configured for driving said x-ray source and said source of optical radiation to emit, respectively, an x-ray beam towards the product sample and an optical-radiation beam towards the same product sample at one and the same time, said apparatus being characterised in that it is configured for driving operation of said x-ray fluorescence apparatus as a function of the values of said second received signal generated in said optical-spectroscopy apparatus, in particular for enabling emission by said x-ray fluorescence apparatus. - a processing module configured for processing said measurement signals (Y1, Y2, Y3; YZ) supplied by said at least two measurement apparatuses (30, 40, 50; HZ) and obtaining properties of said product sample, said quality control being carried out as a function of said properties of said product sample, said at least two apparatuses (30, 40, 50, HZ) for the measurement of properties of a product sample further comprising: - an x-ray fluorescence apparatus comprising an x-ray source, which emits a first x-ray beam (XB, XBC) towards said product sample in a measurement environment, and a particle detector, which is configured for receiving a second x-ray beam scattered by said product sample and for generating a first received signal supplied within the set of said respective measurement signals (Y1, Y2, Y3, YZ), - an x-ray fluorescence apparatus comprising an x-ray source, which emits a first x-ray beam (XB, XBC) towards said product sample in a measurement environment, and a particle detector, which is configured for receiving a second x-ray beam scattered by said product sample and for generating a first received signal supplied within the set of said respective measurement signals (Y1, Y2, Y3, YZ), said apparatus further comprises: - an optical-spectroscopy apparatus operating in a frequency band belonging to the range of optical frequencies, preferably operating in the band of the near infrared, comprising an optical-radiation source, which emits a first beam of optical radiation towards a product sample, and an optical sensor configured for receiving a second beam of radiation scattered by said product sample and for generating a second received signal supplied within the set of said respective measurement signals (Y1, Y2, Y3; YZ) and - an optical-spectroscopy apparatus operating in a frequency band belonging to the range of optical frequencies, preferably operating in the band of the near infrared, comprising an optical-radiation source, which emits a first beam of optical radiation towards a product sample, and an optical sensor configured for receiving a second beam of radiation scattered by said product sample and for generating a second received signal supplied within the set of said respective measurement signals (Y1, Y2, Y3; YZ) and said apparatus is configured for driving said x-ray source and said source of optical radiation to emit, respectively, an x-ray beam towards the product sample and an optical-radiation beam towards the same product sample at one and the same time, said apparatus being characterised in that it is configured for driving operation of said x-ray fluorescence apparatus as a function of the values of said second received signal generated in said optical-spectroscopy apparatus, in particular for enabling emission by said x-ray fluorescence apparatus.