Mn K x rays from55Fe were diffracted with detectable intensity by NaCl and LiF powder. A special diffractometer incorporating a 100‐mc55Fe linear source (1.5 mm × 10 mm) was used. Theoretical diffraction efficiency is about 10−5(on the NaCl 200 plane). Diffractometer geometry provided 10−1to 101photons per min at the detector. This order of intensity was observed with a proportional counter, linear pulse amplifiers, and a multichannel analyzer. The three most intense beams of LiF (&thgr; = 20° to 55°) were clearly demonstrated.