###### Abstract
Previous studies on the role of mineral surfaces for the origin of life [15] have been conducted on the surfaces of oxides, silicates, and carbonates, as these are the major components of rocks, allowing the selection and concentration of macromolecules such as amino acids, sugars, and other types of specific molecules; moreover, clays also allowed for the self-organization of lipids. Therefore, the surfaces of these minerals have been helpful in solving the unknowns of the main prebiotic problems, since they were able to synthesize, contain, and organize biomolecules in a prebiotic soup in which the origin of life might have been favored during the Precambrian era. It is important to mention that obsidian, being rich in silica, in recent times might have played a fundamental role as a supportive substance to preserve the collection of silica carbonate compound inorganic structures in alkaline earth metals. This interaction was first studied many years ago. The results obtained by [PERSON] in the last decade of the XIX century demonstrated that these structures are frequently obtained in the presence of the alkaline earth metals [16; 17]. However, whether the silica contained in the minerals or amorphous rocks present in the primeval era of the Earth interacted with the chemical elements that were also present in that era has not yet been evaluated. It has been shown that, regardless of the natural environment in which the mineral-water interfaces interact, a release of ions from the mineral takes place when it dissolves [18]. This possible interaction, together with atmospheric factors [19], might have formed the structure of the protocell, therefore giving rise to the first organism on our planet. With the passing of time, silica was probably replaced by other chemicals like the carbon-based structures in some organisms while still being preserved nowadays in others such as radiolarians, diatoms, and foraminifera. To evaluate whether the silica in igneous rocks participated in the formation of these first inorganic structures protecting the pioneering organisms like cyanobacteria covered with silica-iron (III) layers [20], we needed to synthesize calcium and barium silico-carbonates (usually called biomorphs) on obsidian, which, as we have already mentioned, is rich in silica. Biomorphs are the ideal models to carry out this type of research because, in addition to being one of the first inorganic structures that protected and isolated the first Precambrian biomolecules on Earth, they are possibly reminiscent of the Precambrian cherts [21]. These biomorphs were obtained for the first time by the Mexican biologist [PERSON] in the last part of the nineteenth century and at the beginning of the twentieth century [16; 17]. Calcium, barium, or strontium silica-carbonate biomorphs are self-organized crystalline materials that display a variety of biomimetic morphologies and a variety of lifelike shapes. These biomorphs show unique curved forms resembling worms, corals, stems, flowers, and leaves, among others, which greatly deviate from the restrictions of classic crystallographic symmetry. Biomorphs are all formed on a silica network (chemically defined as polysiloxane) with calcium, barium, or strontium carbonates deposited on the surface of the silica films [22; 23; 24; 25; 26; 27]. In this contribution, we carried out the synthesis of calcium and barium silica-carbonates on obsidian under two separate atmospheric conditions in order to see how this igneous rock influences the shape of the biomorphs.