Abstract
Emeleusite, Na2LiFeIIISi6O15, is orthorhombic, space group Acam with a = 10.072(3) Å, b = 17.337(6) Å and c = 14.004(3) Å, Z = 8. X-ray data were collected on a four-circle diffractometer to give 563 independent reflections with I > 3 σ (I). The structure was solved by means of Patterson technique followed by Fourier syntheses and refined by least squares to Rw = 0.043.
The structure consists of corrugated double silicate chains with a six tetrahedral repeat (sechser doppelkette). The double silicate chains are linked by chains of Na(2) polyhedra and chains of alternating Li tetrahedra and Fe octahedra. Na(1) is located on the mirror plane coordinated by nine oxygens.
Emeleusite is isostructural with tuhualite, zektzerite and Na2Mg2Si6O15, and more distantly related to the milarite group.
