Linked from
The 48 pages that link to Crystal system, each with the reason it gives.
MagnetiteRelated: Magnetite crystallizes in the cubic crystal system.
Crystal habitRelated: A crystal’s symmetry limits the forms available to its habit.
Mineral collectingRelated: Crystal symmetry helps collectors recognize and compare mineral forms.
AugiteRelated: Augite’s monoclinic symmetry helps distinguish it from orthorhombic pyroxenes.
Crystal opticsRelated: Crystal symmetry constrains which optical anisotropies are possible.