XRDT study of spinel magnesium aluminate natural crystals.: 121 2 1 {1 3̄ 5} 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 1̄ 0 {1 1 0},1 1̄ 0 {1 1 1} and 0 1 1 {1 0 0} — have not been found in any of the two samples. Growth dislocations of strong edge character — 121 2 1 {1 3̄ 5} — not reported till now have been characterised.