DFSAI, JOHN investigated on the dislocation etching behaviour of the Czochralski grown forsterite (Mg,SiO, ; F O , ~) which was obtained from Oak Ridge National Laboratory, U S A . They found that dislocation etch pits were produced on the cleaved (010) faces of the crystals when they were etched either in hydrochloric acid or its vapour, as well as in the melt of KOH. However, suitable etchants for (100) and (001) faces of the Czochralski grown forsterite (Fo,,) could not been found.
Whereas, WEGNER, CHRISTIE reported an etchant for revealing the dislocation sites on the (OIO), (100) and (001) planes of Fe-bearing natural olivines (terrestrial and lunar olivines) ranging in composition from Fo,, to Fo,,. Their etchant was composed of 1 part by vol. conc. HF, 1 part by vol. conc. HCl and 1 part by vol. citric acid saturated solution. But this etchant did not attack the dislocation sites on the (OIO), (100) and (001) planes of the Czochralski grown forsterite (Fo,,) (INOUE et al.).
There have been no suitable etchants for revealing the dislocation sites on the (100) and (001) faces of the Czochralski grown forsterite (Foloo).
So, we investigated reliable dislocation etchants for the (100) and (001) faces of the Czochralski grown Fo,,. A new etchant was found by modifying the etchant by WEGNER, CHRISTIE, i.e., by replacing citric acid with H,O. This new etchant was prepared by mixing: