Recent X-ray single-crystal diffraction studies have shown that CuFeSe 2 crystallizes in the tetragonal system with space group P 2c [ , No. 112], Z = 4, with a =5.530(1) Å and c = 11.049(2) Å, c/a = 1.998. This material had been reported as pseudocubic with a =5.53 Å. The purpose of this paper is to present new X-ray powder diffraction data for CuFeSe 2 and to compare the results with those reported for eskebornite, a mineral with ideal chemical composition CuFeSe 2 , and with those obtained from single-crystal structure data.
