Table 2. Twin fraction (α) determined from diffraction data.

			Twin-fraction (α) estimate
	Twin law	R observed	Britton test	H-test	ML
3.0 Å data set	(h, −h −k, −l)	0.431	0.055	0.060	0.048
2.6 Å data set	(h, −h −k, −l)	0.108	0.399	0.409	0.478