They were generated using a cad software that's been around for about 30 years. The specific rotate/extrude command was executed with the insertion of 'unconventional' (i.e., arbitrary, random and/or irrational) parameters, however.
Actually, the top and bottom group were generated using a supplemental cad software that, as far as I know, doesn't exist anymore. The data generated with that supplemental cad software still exists though.
The cad software used was not grasshopper. Having just watched a couple of grasshopper videos on youtube, grasshopper is much more sophisticated than the software I used. In many ways, I'm stuck in the dark ages of cad software.
In September 2001, while seeing a display of quartz crystals (each labeled as to its geographic origin) compiled over 100 years ago, I thought it would be cool if the buildings of any global location started to match the formations of the local quartz. It was after seeing Harz Mountain quartz that the idea crystallized.