Mineralogical Characteristics Of Major Qingtian Jelly Jade

Qingtian stone (jelly jade) is a carving stone for carving art and seal, being a Literati’s favorite, has therefore been called one of "China’s four seal stones" and its sculpture art is an art of state.Qingtian stone has different varieties of jelly-like stone. The traditional view has been that Qingtian stone is a pyrophyllite mineral. Researches on Qiangtian stone has focused on carving art and culture, its mineralogy do relatively little studied. Also, because Qingtian Stone is mainly finely dispersed layered silicate minerals, modern testing technology must been used to identify its minerals.The author visited Qingtian stone ore deposits, local artists, and collected10jelly-like varieties of Qingtian stone. This paper intends to apply modern mineralogical methods such as polarized light microscopy, scanning electron microscopy, three-dimensional laser scanning confocal microscopy, combined with powder X-ray diffraction techniques, infrared spectroscopy, differential thermal analysis techniques, to make understanding the mineral characteristics of Qingtian jelly stone. We obtained the result based on the10species:(1) Fengmenqing is a green varieties consisting mainly of sericite and pyrophyllite, is a sericite-pyrophyllite mixed Qingtian jelly jade. Compared with industrial pyrophyllite produced in Fangmen area, Fengmenqing has the same chemical composition but alkali-rich, aluminum-rich, silicon-poor, which is the reason because the Fengmenqing rarely contain quartz and contain small amounts of kaolinite.(2) Dengguangdong is a pure pyrophyllite with small amount of quartz.(3)Huangjinyao is also a relatively pure species of pyrophyllite with small amount of quartz. It contains goethite which result in banded yellowish brown color.(4) Baixian (frozen-like) in Dengguangdong is caused by topaz crystals and hence higher hardness.(5) Lanxing (blue star) is based by pyrophyllite and sericite, interspersed with spherical aggregates dumorierite and andalusite aggregates, with small amount of kaolinite. Where the bright blue color caused by dumortierite.(6) Lanhuading (blue flower nail) is mainly in the basal pyrophyllite, blue dotted with clumps of the gray-blue mass of microcrystalline corundum aggregates, there are a small amount of diaspora and kaolinite.(7) Shaobaolu is a species of chromium-sericite, with minor quartz and andalusite. Its bright green is due to Cr-sericite. (8) Longdanshi’s (dragon egg stone) center part is a pure sericite, while Longdanxue (dragon blood) in the out ring of Longdanshi is mainly sericite with pyrophyllite, containing a small amount of scattered hematite, which made a blood color in edge.Presences mineral impurities in Qingtian jelly jade make it poor-polishing, weaker waxy luster. However, the occurrence of various impurities minerals made Qingtian jelly jade many diversities with rich colors.Mining of Qingtian stone has a long history more than1700years, remaining many ancient mines. We proposed that measures must been taken to protect the historical remaining sites in order to promote Qingtian jelly jade’s culture and science.