XRDT study of spinel magnesium aluminate natural crystals. ½[121](1-35) growth dislocations

The growth dislocations of two natural spinel crystals from Pegu (Burma) have been studied by X-ray diffraction topography. The dislocation systems reported in literature — <1-10>(110),<1-10>(111)and <011>(100)— have not been found in any of the two samples. Growth dislocations of strong edge character — 1/2<121>(1-35)— not reported till now have been characterised