The crystal structure of hiortdahlite I (triclinic, {Mathematical expression}, a=11.0149(9), b=10.9409(9), c=7.3534(3), α=109.350(3), β=109.879(4), γ=83.434(4)) was determined and refined using 2910 reflections to R1=0.058 and R2=0.055. The results of the structure determination confirmed that hiortdahlite presents the features common to the whole series of minerals in the cuspidine group, namely "octahedral walls", four columns large and running parallel to c, interconnected by corner sharing and through Si2O7 groups. The cation distribution in the polyhedral walls and the location of the fluorine anions were determined and discussed. The crystal-chemical formula obtained from the structural study is (Na3.2Ca0.8)Ca8Zr2M2(Si2O7)4O2.8F5.2 where M represents a mixing site with average charge three.
THE CRYSTAL-STRUCTURE OF HIORTDAHLITE-I
MERLINO, STEFANO;PERCHIAZZI, NATALE
1985-01-01
Abstract
The crystal structure of hiortdahlite I (triclinic, {Mathematical expression}, a=11.0149(9), b=10.9409(9), c=7.3534(3), α=109.350(3), β=109.879(4), γ=83.434(4)) was determined and refined using 2910 reflections to R1=0.058 and R2=0.055. The results of the structure determination confirmed that hiortdahlite presents the features common to the whole series of minerals in the cuspidine group, namely "octahedral walls", four columns large and running parallel to c, interconnected by corner sharing and through Si2O7 groups. The cation distribution in the polyhedral walls and the location of the fluorine anions were determined and discussed. The crystal-chemical formula obtained from the structural study is (Na3.2Ca0.8)Ca8Zr2M2(Si2O7)4O2.8F5.2 where M represents a mixing site with average charge three.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
