Upon analyzing the structure of both ettringite and thaumasite, it was deduced that both minerals have hexagonal structures, but different space groups. Ettringite crystals have a P31c with a=11.224 Å, c= 21,108 Å, while thaumasite crystals fall into space group P63 with a= 11.04 Å, c= 10.39 Å. While these two minerals form a solid solution, the difference in space groups lead to discontinuities in unit cell parameters. Differences between structures of ettringite and thaumasite arise from the columns of cations and anions: Ettringite cation columns are composed of Ca3which run parallel to the "c" axis, and the other columns of sulfate anions and water molecules in channels parallel to these columns. In contrast, thaumasite consists of a cylindrical column of Ca3[Si(OH)6·12H2O3+ in the "c" axis, with sulfate and carbonate anions in channels between these columns which contain water molecules as well.