Cubic crystals are not always cubic! There are many shaped like octahedrons (eight faces), and others shaped like dodecahedra (12 faces).
Tetragonal crystals are shaped like cubic crystals, but are longer by one of their faces, creating shapes similar to double pyramids and prisms.
The orthorhombic crystals are in the form of rhombic prisms or dipyramids (two glued pyramids). They tend to look like tetragonal crystals, only they are not square in cross-section (when you look at the glass from one end).
Hexagonal crystals look like prisms of six faces. When looking at the glass from one end its cross section appears to have the shape of a hexagon.
Monoclonal crystals look like tetragonal crystals that have been skewed. They often form prisms and double pyramids.

The Luster in the minerals is itself, the brightness that presents in its surface, the way in which it reflects the light, and can be classified in: Metallic, Submetallic and Non-metallic. Non-metallic minerals can be subdivided into: Adamantine, Resin, Glazed or crystalline, Perlescent, Oily, Silky, Matte and Earthy.

The color in the minerals is determined by the ability to absorb or reflect certain wavelengths of light, this capacity depends on its chemical composition, each element and chemical component has its own atomic structure and its interaction with light determines the quantity and The type of wavelengths that are absorbed or reflected, it is known that the presence of some elements produces a certain color in a wide variety of minerals, even in small quantities, thus, iron produces red and yellow tones, or copper, Which produces blue and green tones, but this is not always the same, other chemical combinations can produce the same colorations, this means that we can not try to identify a mineral based only on its coloration, as examples we can mention the Iron, which produces red tones -an orange in Limonite, but also Vanadium produces similar colorations in Vanadinite as well as Chromium in Crocoite, examples of the presence of some elements and their influence on the coloration of minerals are:

It is called tenacity to resistance that opposes a mineral to be broken, ground, bent or torn, being, in a way, a measure of its cohesion.

A series of objectives related to this concept are defined:

Hardness is the opposition that materials offer to alterations such as penetration, abrasion, scratching, shearing, and permanent deformations among others. In the course of history, during the study and classification of minerals, there was a moment when it became pertinent to establish a method that would allow to discern the different degrees of hardness of rocks and minerals. The first attempt to establish a procedure for this purpose, unscientific, but in practice quite professional, was due to Friedrich Mohs. Its simplicity (both memorization and application) has strengthened it in this position, since it can be used in the fieldwork of geologists.