Pyrites, crystal symmetry

In Figure 99, we also show photographs of some pyrite crystals. As you can see, these crystals are considerably distorted from the idealized symmetries that we have discussed. Notice also that the faces of some of the cubic crystals have striations in a direction perpendicular to the striations on neighboring faces. This is a result of the lower symmetry of the 2/m3 class, where, for example, the four-fold axes that would generate identical cube faces, are absent. 

Il Is significant to note that in most geometrical siluations regarding crystal study, the distinguishing characteristic is symmetry, not geometry. This is especially true in the case of a mineral such as pyrite (l eS I which assumes a cubic shape, but its symmetry, controlled by the three sets of... 

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