Petrochemistry Characteristics and Genesis of Hongsi Inkstone from Linqu， Shandong Province

Hongsi inkstone is popular because of its yellow and red colour and the filiform patterns.Hongsi inkstone was originally mined from Heishan in Qingzhou,Shandong Province,during the reign of Emperor Zhonghe years(881-884 A.D.)of Tang Dynastv.However,it was said that the stones exhausted at the end of Song Dynasty,and then were mined again from Qing Dynasty in the Laoyagu area in Linqu,Shandong Province。The Hongsi inkstone is not only good for ink-making,but also has fancy patterns and colour,which is extraordinary popular among the calligraphers and painters at all times and all over the world.
At present,researches on Hongsi inkstone are limited to the history,culture,identification and evaluation,etc,and less on petrochemistry and deposit genesis.
The geochemical compositions of the major elements,trace elements and rare earth elements of Hongsi inkstone samples from Linqu in Shandong Province were studied by whole-rock chemical analysis.The conditions for the genesis of Hongsi inkstones were speculated by the ratios of representative elements.The results show that Hongsi inkstones are the carbonatite with the high content of CaO.The content of SiO₂ ranges from 3.38%to 7.87% with the average of 5.30%.The content of Al₂O₃ ranges from 0.75%to 1.74% with the average of 1.22%.The content of FeO_T ranges from 0.65%to 1.43% with the average of 1.04%.The high content of CaO ranges from 32.84% to 53.10% with the average of 47.69%.The content of MgO ranges from 0.64% to 14.88% with the average of 3.92%. The high content of LOI ranges from 37.97% to 44.44%,with the average of 40.15%.The data above accord to the common chemical characteristics of the limestone.The ratios of Mg/Ca,SiO₂/(K₂O+Na₂O),Al₂O₂/(K₂O+Na₂O)and Mn/Fe show the characteristics of the sedimentary carbonatite and the littoral facies sediment.
The contents of trace elements in Hongsi inkstone samples have significant change,the obviously higher contents of P,Ti,Mn,Sr,Ba and the slightly higher contents of Cr,Zn, Ni,which display the characteristics of the interactive marine-land shallow water environment in tidal-flat facies according to the ratios of Sr/Ba,Sr/Ca and Th/U.
The contents of rare earth elements range from 10.76×10^-6 to 25.86×10^-6 with the higher contents of La,Ce and Nd and the lower contents of Tm and Lu,which show the lower chemical contents than the compositions of continental crust.It displays the genesis characteristics of the sedimentary carbonate rocks by using the ratios of LREE/HREE, ω(La)/ω(Lu)_N,ω(La)/ω(Yb)_N of the rare earth elements and the values of δEu and δCe,and figure of Yb/La—Yb/Ca.