Cu-63 MAS NMR spectra of CuX crystals (X = Cl, Br, and I) and CuX-based glasses (X = Cl, Br, and I) have been measured. The CuCl and CuI crystals gave the isotropic chemical shift values around 0 ppm, and the CuBr crystal, around -55 ppm. The peak positions of the chlorocuprate(I), bromocuprate(I), and iodocuprate(I) glasses were very close to those of the CuX crystals, respectively. This result indicates that these glasses mainly consist of CuX4 tetrahedra (X = Cl, Br, and I). The halogen coordination environments around Cu+ in bromochlorocuprate(I) glasses were dependent on the kind of modifying cation and the Br-/(Cl- + Br-) ratio. The bromochlorocuprate(I) glasses were mainly composed of CuClmBr4-m or CuClnBr4-n tetrahedra (m = 0, 1, 2, and 4; n = 0, 1, and 4). (C) 2002 Elsevier Science Ltd. All rights reserved.