The palmierite supergroup, approved by the IMA-CNMNC, includes five mineral species characterised by the general crystal-chemical formula XIIM1XM22(IVTO4)2 (Z = 3). On the basis of the crystal-chemical arguments and heterovalent isomorphic substitution scheme M++T6+ ↔ M2++T5+, the palmierite supergroup can be formally divided into two groups: the palmierite group M12+M22+(T6+O4)2, and the tuite group M12+M222+(T5+O4)2. Currently, the palmierite group includes palmierite K2Pb(SO4)2, and kalistrontite K2Sr(SO4)2, whereas the tuite group combines tuite Ca3(PO4)2, mazorite Ba3(PO4)2, and gurimite Ba3(VO4)2. The isostructural supergroup members crystallise in space group R$\bar{3}$m (no. 166). The palmierite-type crystal structure is characterised by a sheet arrangement composed of layers formed by M1O12 and M2O10 polyhedra separated by TO4 tetrahedra perpendicular to the c axis. The abundance of distinct ions, which may be hosted at the M and T sites (M = K, Na, Ca, Sr, Ba, Sr, Pb, Rb, Zn, Tl, Cs, Bi, NH4 and REE; T = Si, P, V, As, S, Se, Mo, Cr and W) implies many possible combinations, resulting in potentially new mineral species. Minerals belonging to the palmierite supergroup are relatively rare and usually form under specific conditions, and their synthetic counterparts play a significant role in various industrial applications.

Palmierite (K2Pb(SO4)2) has been prepared via a chemical synthesis method. Intensity differences were observed when X-ray powder data from the newly synthesized compound were compared to the published powder diffraction card (PDF) 29-1015 for Palmierite. Investigation of these differences indicated the possibility of preferred orientation and/or chemical inhomogeneity affecting intensities, particularly those of the basal (00l) reflections. Annealing of the Palmierite was found to reduce the effects of preferred orientation. Electron microprobe analysis confirmed K:Pb:S as 2:1:2 for the for the annealed Palmierite powder. Subsequent least-squares refinement and Rietveld analysis of the annealed powder showed peak intensities very close to that of a calculated Palmierite pattern (based on single crystal data), yet substantially higher than many of the PDF 29-1015 published intensities. Further investigation of peak intensity variation via calculated patterns suggested that the intensity discrepancies between the annealed sample and those found in PDF 29-1015 were potentially due to chemical variation in the K2Pb(SO4)2 composition. X-ray powder diffraction and crystal data for Palmierite are reported for the annealed sample. Palmierite is trigonal/hexagonal with unit cell parameters a=5.497(1) Å, c=20.864(2) Å, space group R-3m(166), and Z=3.