Strontianiferous aragonite occurs at the Yanzidong Cu deposit in the northern part of Lanping basin, Yunnan Province. Examination by such means as X-ray, EMB, test of microhardness and index of refraction together with gemological studies have revealed that this strontianiferous aragonite is a special kind of aragonite, the change of the crystal lattice and genesis of the colour have also been analyzed. In addition, the advantage and possibility of the application of the aragonite as a kind of gem have been studied.