Calcium pyrophosphate dihydrate (CPPD) crystals deposition disease or " pseudogout " is an arthropathy rarely affecting the temporomandibular joint (TMJ). Less than 30 clinical cases are reported in literature, whereas mineralogical, structural and chemical studies on CPPD crystals are very few and concern only data on synthetic phases. Medical and mineralogical studies were carried out on CPPD crystals deposition in TMJ area of a 63-year-old woman operated in the 2010. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) investigations were performed to identify the phosphate crystals and to understand the mechanism of their formation. Two phosphates were characterized: a monoclinic (m-CPPD) and a triclinic (t-CPPD) phase, which are the natural analogues of synthetic phases. It is likely that the crystallization of two phosphates during this human disorder was originated by a catalyst activity. One option is to rely on the activity of the bacteria or cellular enzymes during the first stage of the growth of these minerals.