Improved powder X-ray data for the cement phase Ca12O32F2 (C11A7f)

A chemical and mineralogical investigation of a Moroccan pyrophyllite is presented. X-ray powder diffraction has been largely used for phase identification and crystal symmetry determination. It is shown that this mineral has a triclinic symmetry with cell parameters: a=5.160 A, b==8.993 A, c=9.360A, (alfa)=90.77°, (beta)=100.57°, and (gamma)=89.71°