In crystallography, the law that describes how an X-ray beam is reflected or diffracted in a crystal lattice, given by the Bragg equation nλ – 2dsinϴ where n is any integer, λ is the wavelength of the incident-beam X-ray, d is the spacing between crystal planes (d spacing), and ϴ is the angle between the crystal plane and the diffracted beam (the Bragg angle). Used in X-ray diffraction for the identification of minerals.