NordenskiSldine, a rare nesoborate mineral, was found in a fluorite deposit in Wuxian county, Jiangsu province in 1983. Its optical and physical properties are as follows: uniaxial negative with No=1.774(±0.0015) and Ne=1.661(±0.0015);gravity 4.09; distinct(0001) cleavage; colour milky white but greyish white in the thin section. Its composition is determined as SnO2 51.26%，Ca0 20.48%，B2O5 25.0%， Fe0 0.4%，MgO 0.14%，SiO2 0.39% and TiO2 0.14%，giving a chemical formula of (Ca1.02Mg0.011El0.017Ba0.002)1.050Sn0.96(BO3)2. Being a skarn minexal, it occurs at the contact zone between the granite intrusive body and the marble. The discovery of such a rare mineral not only r eveals new occurrence of this mineral, but also casts some new light on the geochemistry of Sn and B.