Abstract：Clinical Chinese Medicine commonly used gypsum (CaSO4·2H2O) to treat febrile diseases. Based on the study of microscopic crystal characteristics and trace element characteristics of gypsum, the hypothesis that trace element strontium (Sr) is an important influential element for gypsum cooling is proposed. We analyzed the microscopic crystal structure and trace element composition of 33 batches of gypsum herbs from five producing areas by optical polarized light microscopy (OPLM), X-ray diffraction (XRD), electron probe micro-analysis (EPMA) and inductively coupled plasma mass spectrometry (ICP-MS). The results of OPLM analysis show that the microscopic morphology of gypsum is mainly long columnar and fibrous, and is related to the original area of gypsum. According to the traditional requirements, the samples with good quality have larger micro-particles. XRD analysis showed that except for one batch of samples containing quartz impurities, the other samples showed no other mineral impurities. The results of EPMA analysis showed that the main mineral in the gypsum sample was gypsum and the secondary mineral was anhydrite, which showed a symbiotic relationship. The anhydrite in the micro-area image has no definite crystal form, and the contact surfaces of anhydrite and gypsum are irregular curves. It is speculated that the anhydrite is converted from the gypsumin the later stage of mineralization rather than native. The results of ICP-MS analysis showed that the trace element strontium (Sr) was higher in gypsum, and the highest absolute content of all trace elements. The comparison with trace elements in the primitive mantle showed that the Sr element is the most stable and enriched trace element in the gypsum sample, which is more than 6 times more than the primitive mantle, up to 176 times. The analysis of the value of CaO/SrO in the micro-site of gypsum shows that the strontium (Sr) element is statistically uniformly distributed in the gypsum and exists mainly in the form of isomorphic mixtures in gypsum. The results of the determination of the Sr element content in the aqueous gypsum solution showed that the dissolution amount of strontium (Sr) in the gypsum decocted fluid and the gypsum suspension reached 2～4 times of the theoretical value. Gypsum was used in large doses in the clinic, and decocted first can promote the dissolution of Sr2+. Because Sr has the effect of inhibiting Na. The hypothesis of gypsum cooling: when gypsum is used for cooling, Sr2+ and Ca2+ are simultaneously dissolved. Sr2+ inhibits the absorption of Na+ to the body, increases the supply of Ca2+ to the body, and regulates the ratio of Na+/Ca2+ one of the positive regulation medium of fever. The material basis for the cooling of gypsum is the joint action of Sr and Ca.
Key words：Gypsum; Electron probe microanalysis; X-ray diffraction; Sr element；CaO/SrO; Na+/Ca2+
[1] ZHANG Xi-chun(张锡纯). Medical Zhong West recorded(医学衷中參西录). Taiyuan: Shanxi Science and Technology Press(太原：山西科学技术出版社), 2009. 193.
[2] GUO Xie-xun, LU Ru-xun(郭协埙, 陆汝逊). Shanghai Journal of Traditional Chinese Medicine(上海中医药杂志), 1958, 3: 33.
[3] XIA Yi, LI Xiang, CHEN Jian-wei, et al(夏 怡，李 祥，陈建伟，等). Research and Practice on Chinese Medicines(现代中药研究与实践), 2009, 23(2): 48.
[4] LI Xuan-zhen, WANG Xi-xia(李轩贞, 王锡霞). Journal of Chinese Medicinal Materials(中药材), 1990, 13(4): 35.
[5] WANG Huan-di, WANG Meng-yue, LI Xiao-bo(王焕弟, 王梦月, 李晓波). Chinese Journal of Pharmaceutical Analysis(药物分析杂志), 2009, 29(3): 437.
[6] WANG Wei, ZHOU Cai-xin, ZHANG Yi-sheng, et al(王 薇, 周才新, 张义生，等). China Pharmacist(中国药师), 2014, 17(6): 972.
[7] TIAN Teng-yue, BAO Yong-rui, MENG Xian-sheng, et al(田腾跃, 包永睿, 孟宪生，等). Chinese Archives of Traditional Chinese Medicine(中华中医药学刊), 2017, 4: 1041.
[8] LIU Yuan-fen, LI Xiang, GAO Jin-biao, et al(刘元芬, 李 祥, 高锦飚，等). Research and Practice on Chinese Medicines(现代中药研究与实践), 2007, 3: 35.
[9] SUN Shu(孙 姝). Chinese Medicine Modern Distance Education of China(中国中医药现代远程教育), 2009, 7(5): 170.
[10] ZHOU Hao(周 灏). Acta Chinese Medicine(中医学报), 2015, 30(6): 860.
[11] Ortí F, Rosell L, Playà E, et al. Sedimentology, 2012, 59: 1257.
[12] Mcdonough W F, Sun S S. Chemical Geology, 1995, 120(3-4): 223.
[13] Lebedev A L, Kosorukov V L. Geochemistry International, 2017, 55: 205.
[14] Dawson E B, Frey M J, Moore T D, et al. American Journal of Clinical Nutrition, 1978, 31(7): 1188.
