Crystallography in geology ppt

Crystallographers do not have complete answers, but the most important factor is the location of atoms within a unit cell

Crystals of a particular mineral tend to have the same forms, or only a limited number of forms, no matter how they grow

Haüy and Bravais noted this and used it to infer that atomic structure controls crystal forms

A third law of crystallography is that: blank ■The symmetries of the unit cells are the same as the point groups of greatest symmetry in each of the crystal systems

All minerals that belong to the cubic system have cubic unit cells with symmetry 4/m32/m

Their crystals, however may have less symmetry