GROWN-IN DEFECTS IN NATURAL BERYLS BY X-RAY TOPOGRAPHY AND BIREFRINGENCE

The growth sectors and their boundaries, impurity zonings and dislocations in natural beryls hare been observed by means of X-ray diffraction topography and birefringence. The displacements of fault surfaces of the sector boundaries are perpendicular to the fault surfaces. The Burgers vectors of some typical dislocations in (0001) sector are <1120>, <1100> and <1450>. It is found that the techniques of X-ray diffraction topography and optical birefringence are complementary.