Retgersite
tetragonal trapezohedral
this crystal shows 54 faces
pinacoid {001}      d = 0.9500   2 faces
tetragonal prism {100}      d = 1.1000   4 faces
tetragonal dipyramid {101}      d = 1.0750   8 faces
tetragonal dipyramid {203}      d = 1.190   8 faces
tetragonal dipyramid {111}      d = 0.880   8 faces
tetragonal dipyramid {113}      d = 1.050   8 faces
tetragonal dipyramid {112}      d = 0.9200   8 faces
tetragonal trapezohedron {211}      d = 1.0150   8 faces
unit cell :  a = 6.79  c = 18.29