Gemmological Characteristics and Classification of“Taishunshi”as Pyrophyllite-type Seal Stone from Zhejiang Province

Microscope,SEM,XRD and XRF are used to study the gemmological characteristics and classification of"Taishunshi"from Zhejiang Province.The results show that the"Taishunshi"samples are typical pyrophyllite seal stones,which contain more diaspore and alunite than Qingtian stone.In the observation the transparent samples has the uniform structure,and with good lamellar structure it shows a strong waxy luster.The different minerals have different condensation point from that of pyrophyllite,which led to various textures.In the study it shows with the increasing content of Al element,the contents of Si,Fe and Ti reduce,which affect the quality.According to the contents of major elements,the authors think that"Taishunshi"can be classified to pure-pyrophyllite type,high-aluminum pyrophyllite type,high-silicon pyrophyllite type,high-iron pyrophyllite type and high-sulfur pyrophyllite type.Most of high quality"Taishunshi"samples belong to the high-aluminum pyrophyllite type.