Mineralogy: Lecture 7, Crystal Systems 1

[@celinahaddar4494]

First of all great lecture I had so much trouble finding any content on cristallography and yours was just awesome so thank you!!! Second please I have a question to what crystal clans does a square based BIyramide and a hexagonal base pyramide belong to?

[@zoespeshington2401]

I'm not sure I could really follow this one. Is there a reason that a+ is on an opposite plane? I'm not sure I see why the positioning is how it is. Also, part C I can't see how you throw this 'imaginary' lines of symmetry over something that does not have it? Couldn't you just do that for all crystals? It would be wrong but I can't visualise what you mean?