Biomineralization is a process by which microorganisms transform environmental metal elements into inorganic or functional organic-inorganic biominerals through physiological regulation. It consists of biologically induced mineralization (BIM) and biologically controlled mineralization (BCM). The former is regulated by environmental factors such as pH, temperature, dissolved oxygen, and redox potential, whereas the microbial genes control the latter. The biomineralized inorganic functional materials with multi-level ordered structures exist widely in nature, which has interested physicists, geologists, chemists, microbiologists, and material scientists. The intracellular magnetosomes and extracellular iron minerals can be biomineralized by magnetotactic bacteria and iron-reducing bacteria, respectively. Microbial mineralization struvite can reduce the cost of the removal and recovery of sewage nitrogen and phosphorus. Carbonate mineralization mediated by microbes can effectively convert carbon dioxide and organic carbon in the atmosphere into carbonate cement, which is an important carbon sink. Various calcium carbonate mineralization products occur in animals. The calcite can be used as a gravity sensor in the inner ear of mammals and the aragonite is commonly found in the exoskeleton of invertebrates including pearls, shells and phalaenopsis.

Spectroscopy is an important approach for detecting biomineralized products and exploring the process of biomineralization. It can monitor the nanostructure formation and/or changes in chemistry and/or degree of crystallinity of products during microbial mineralization. It also can deduce the synthesis mechanism of mineralized products combined with biological methods. Many spectroscopic techniques such as Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and its second derivative spectroscopy, atomic absorption spectroscopy, inductively coupled plasma emission spectroscopy, X-ray absorption near edge structure (XANES), Extended X-ray absorption fine structure (EXAFS), Electron energy-loss near-edge spectroscopy (ELNES, like XANEBS but with electrons instead of X-rays), and neutron diffraction and scattering, as well as ultraviolet spectrophotometry, Energy Dispersive X-ray spectroscopy (EDXS) can be applied in the field of biomineralization. The variation of phase-mineral and chemical composition during the mineralization of iron ores can be clarified by XRD and Raman spectroscopic analysis. FTIR can also be used to analyze the composition of gallstones, which are biological mineralization products of humans. The contents of Ca, Mg, Zn, Cu, Fe, Mn in gallstones and what they might do can also be analyzed by atomic absorption spectroscopy. XANES and EXAFS combined with advanced synchrotron radiation technology can be applied to detect the valence states and occupancy of isomorphic displacement ions in magnetite structures. ELNES can be widely used to determine the valance states of some transition metals (such as Fe, Co, Ni, etc.) in different compounds. Additionally, the dual approach between spectroscopy and simulations can be utilized for characterizing biomineralized materials.

Although biomineralization appears of great significance in biogeochemistry, it is difficult investigating the processes and products. The theory of spectroscopy and detection technology in the traditional field is relatively mature. We need to make greater progress in the instrument and spectral analysis in biomineralization. The corresponding spectral model should be proposed based on the theoretical analysis and case study. The spectral parameters and their structural information should be determined. Accordingly, the biomineralization process and the relationship between the structure and the property of mineralized products can be more accurately explored.

The aim of this Special Issue is to bring together original research and review articles in this research field.

Potential topics include but are not limited to the following:

• Spectroscopic technology for the characterization of microbial mineralized inorganic materials
• Biologically induced mineralization
• Biologically controlled mineralization
• Microbiological nanominerals
• Investigation of biomineralization with spectroscopy methods