According to its determined mineral components, Shoushan Stone can be classified into nacrite type, dickite type, sericite type and pyrophyllite type. Based on a discussion on nomenclature of Tianhuang Stone, the authors hold that all the Shoushan Stone and seal stones produced in other areas which are up to the nomenclature of Tianhuang Stone should also be called Tianhuang Stone. The ore_forming age of Shoushan Stone determined for the first time by the authors with 40Ar-39Ar method is 133.44±4.69 Ma, which suggests that Shoushan Stone was formed through the replacement of volcanic rock by hydrothermal solutions which were derived from volcanic rock itself and migrated along faults or shatter zones after the eruption of acid volcanic rock in late Jurassic.