An attempt was made to determine the true symmetry of the cleavage flakes of aramayoite by means of the Laue photographic method. Since X-ray diffraction takes place within the crystal, the lack of welldeveloped faces other than main cleavage faces was no disadvantage. One feature, however, which did prove a difficulty, was the pliability of thin clevage flakes referred to by Dr. Spencer. It was essential that the whole of the main cleavage face upon which the X-ray beam was incident should be strictly perpendicular to that beam. In order to ensure this, only those flakes were used which gave a single optical reflection, and two distinct methods of setting were resorted to. In the first case the slit (circular aperture) was used vertically ; the flat end of the slit system was ground truly perpendicular to the slit itself and was thus horizontal.