Abstract: Traditionally,"ink" jade is black nephrite, whose colour is caused by the graphite as its inclusion. A kind of "black jade "is often encountered in market, whose appearance, refractive index and density are almost close to that of the black nephrite. In this article, the "black jade "is studied, and it is found out that the main composition is dark green hornblende, so the jade must not be named "ink" jade but hornblende jade.