Etch figures on gallium orthophosphate (GaPO4) crystals are presented for t
he {0 0 1}, {0 1 0}, {2 (1) over bar 0}, {(2) over bar 1 0} and (1 0 1} fac
es. Primarily they are used in detecting possibly occurring domains of twin
ning. Generally, the etch figures of GaPO4 show similarities as well as dif
ferences compared to those of low-quartz modifications of SiO2 and AlPO4. (
C) 2000 Elsevier Science B.V. All rights reserved.