The aim of this paper is to review in very general and fast key relationships between soil genesis, mineralogy, fertility and behavior, to achieve this, it is a quick review of key concepts compiled as a result of the consultation articles and books mainly from some Colombian authors with extensive experience in this field. To understand the mineralogy of the soil fractions and its relationship with fertility, it is necessary to note that the soil mineral fraction is composed of the coarse fraction (sand and silt) and fine fraction (clay). The coarse fraction is a potential reservoir of nutrients and the clay fraction determines the physicochemical behavior of the soil, given by its activity (Mejia 1980).