Etude des défauts dans des monocristaux naturels de topaze. II. Etude de genèse

Two samples of monocrystal topaz from Nigeria and Brazil are studied by X-ray topography. The plates are obtained by cleavage and in both growth bands are observed. These bands are parallel to the different faces of the morphology and are grouped in sectors. The limits between two adjacent growth sectors induce more or less misorientation. Observations of topographs allow the reconstruction of different stages of crystal growth.