Some of these crystals have several curious features. (1) The bipyramids are longer on the bottom than on the top, as pictured in Fig. and. The length of the top pyramid is 75-80% of the bottom. (2) The bottom pyramid is more acute than the top, albeit this apparent angle depends upon the azimuth of the micrograph with respect to the vertical axis. The angle of the top pyramid is near 55° in projection whereas the angle in the bottom pyramid is closer to 45°. These morphologies are consistent with the polar point group 6, as opposed to 622 where the top and bottom are equivalent. The sense of this axis could be a growth variable that makes some crystals appear symmetric on top and bottom. (3) The interfacial edges that separate the top and bottom pyramids have long and short bounding edges, horizontal and inclined, respectively. We have found that the best way to approximate this intersection is with two types of pyramids: the bottom pyramid with isohedral faces {111 % } and the top pyramid with enantiomorphous faces either {122} or {212}. In contrast, symmetry 622 with twelve {111} facets, i.e., symmetry 6 with six {111} facets and six {111 % } facets would give a bipyramid with edges between the large faces of top and bottom pyramids nearly parallel to the intersecting planes. (4) Interpenetrated twinned crystals (RR, LL, and RL) were also observed as clearly seen by micro-CT (Fig. ).