The diversity of biominerals produced by living organisms in respect of varying composition and structure is very remarkable. Many of these biominerals are highly complex composite materials with excellent physical and mechanical properties [1,2] which cannot be mimicked in laboratory. The combinations of organic matrix and amorphous and crystalline minerals formed under conditions of moderate temperature, pressure and pH possess masterpiece architectures with superior materials characteristics

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... compared to geological counterparts or their synthetically made analogues [2,3]. Rodents possess opposing long pairs of continuously growing incisors that are worn down by gnawing. The front part of the incisors is enamel, which is the hardest tissue of the body containing 96 wt% of inorganic material; the inner part is softer dentine that forms the bulk of the teeth [4]. Surface of incisors of several different rodent species shows characteristic orange-brown colour and is identified with the presence of iron [5] . Based on electron microprobe characterization of the enamel surface layer [6] the amount of iron is 10-30 wt%. In the present study, upper and lower incisors of the feral coypu (Myocastor coypus Molina) were investigated. The microstructure and chemical composition at the enamel surface and in dentine were studied in detail by using energy-dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) combined with scanning transmission electron microscopy (STEM) at high spatial resolution using a VG HB501UX and the Zeiss SESAM microscopes.