A group of M
2+-M
3+-oxysalts (phosphates, arsenates, vanadates, sometimes also containing sulfate) where M
2+ = Ca, Ba, Sr, Ba and M
3+ = Al, Fe, Mn, ... (sometimes replaced by medium-small M
2+ cations such as Zn
2+, Fe
2+, Cu
2+). Named after the member
brackebuschite.
Different space-group symmetries are known, confirming the close relation to
fornacite and
vauquelinite (U. Kolitsch et al., unpublished data).
