Why does the mineral pyrite have many shapes?
Pyrite can form in a myriad of different crystal habits. Primary pyrite habits such as framboid, colloform and spheroidal textures are those most often associated with growth in soft sediments. Cubes and the more characteristic forms are associated with increased P-T conditions and recrystallisation. So, the reason pyrite has many shapes is because it can be found in virtually every rock type, it is generally rigid and stable at temperatures up to ~743 degrees and so throughout its history it will be affected by a number of different factors which may alter crystal forms.