The present paper deals mineralogically with the collophane collected from phosphorites in Dianchi area, Yunnan province in respect to its physical properties, chemical composition and genetic mechanism. On such a basis, it holds that collophane occurs mainly in three forms in phosphorite: gelatinous, intraelastic and bioclastic. SEM studies of all the three types demonstrate that this colloidal mineral is made up primarily of supermicroscopic low-carbonate fluorapatite aggregates, phosphate microframboids, and radiated fibrous apatite.Chemical and infrared analysis, together with the measurement of cell parameters, clearly shows that different types of collophane differ more or less from each other, especially in contents of CO2 and P2O5. A comparison of mineralogic characteristics indicates that, with the advance in diagenesis and metamorphism, collophaae tends to evolve into crystalline fluorapatite and exhibits obvious decarbonization.REE geochemistry of the collophane typifies a high abundance of yttrium group elements, showing a cerium-deficient pattern after chondrite-normalization.All this suggests that the collophane has a close genetic linkage with, among others, a higher fo2 prevailing over the geochemical barrier.