Crystal structure of rhodesite, HK1 −xNax+ 2yCa2 −y{lB,3,2∞2}[Si8O19] · (6 –z) H2O, from three localities and its relation to other silicates with dreier double layers

Rhodesite from Zeilberg, Unterfranken, Germany (Z), from Trinity County, California, USA (TC), and from San Venanzo, Rieti, Italy (SV), is orthorhombic with space group Pmam.