Abstract: Maanshan district of Anhui Province is fruitful of the apatite-pseudomorphic turquoises.The X-ray powder diffraction analysis,infrared absorption spectrum,chemistry analysis and differential thermal analysis have been employed to discuss the features of gem-mineralogy of this kind of turquoise in this paper.It has reached a conclusion that the colour of the turquoise results from the electronic transition between orbits of hydrated ions Cu(H₂O)₄²⁺ and Fe(H₂O)₆³⁺.The existent form and content as well as the combining mode of H₂O control directly the colour of the turquoise.Moreover,the intensity of the supergene weathering affects the colour,compact degree and the luster of the turquoise to some extent.