All combinations of possible symmetry elements (and some single elements) are referred to six crystal systems. which are these six?

There are a total six crystal system like triclinic, monoclinic, tetragonal, hexagonal, orthorhombic and cubic.

Explanation:

The crystal forms of the crystal family refer to several classes of crystals that are informally formed by the grouping of crystal and being divided based on sources. The crystal; system that corresponds to space groups is given a lattice system giving them a 32 point scale. These points are assigned to the trigonal crystal system which consists of all the above 6 system forms of crystals. Their name is given by Whittaker who formed these crystal structures as protein structures