[ccp4bb] crystal habit/morphology and the relationship to unit cell contents

[Paul Paukstelis]

I'm interested in knowing how to figure out the relationship between the 
unit cell contents and the crystal habit in these crystals (small 
attachment, two roughly orthogonal views).

Space group is P64 (enantiomeric) , and you can clearly see the 
six-fold. The question becomes how to determine which direction the 
screw axis is going with respect to "top" and the "base" of the 
pyramidal crystals (right image) so I can gauge how/why the crystals 
grow this way based on the cell contents.

Thanks in advance.

--paul