浙江方家山高岭土矿床中高岭石亚族矿物的研究

珍珠陶石、地开石和高岭石是高岭石亚族矿物的三种多型。其中高岭石最常见,地开石较少见,而珍珠陶石是十分罕见的多型。本文作者应用Ｘ射线衍射、红外光谱和醋酸钾夹层化合物的方法,研究了浙江方家山高岭石矿物特征。研究表明,用醋酸钾为夹带剂形成的珍珠陶石夹层化合物具有１４．０的特征衍射峰,经水分子取代后形成８．３５特征的珍珠陶石水合化合物,而高岭石仅部分形成７．３０水合夹层化合物。从而确定了方家山高岭土矿床是以高岭石为主含珍珠陶石的矿床,其珍珠陶石主要赋存于粗粒级的高岭土中。高岭石与珍珠陶石晶畴呈消长关系可能说明珍珠陶石是后期较强应力下由高岭石转变来的。

A Study of kaolinite Minerals from Fangjiashan,zhejiang Province

Kaolinite, dickite and nacrite are polytypes of the kaolinite family, in which kaolinite is quite common while nacrite is very rare in nature. As is well known, different kaolinite polytypes occur in different gelogical environ- ments. Nacrite usually appears in an environment with relatively high tem- perature and pressure. Therefore, it is of great significance in theory and practice to distinguish kaolinite polytypes in detail. Characteristics of the kaolinite family from the Early Carboniferous Fang- jiashan kaolin deposit were studied by means of X-ray diffraction, infrared spectroscopy and potassium acetate intercalation. With the entrainer of K-acetate acted on the kaolin, an intercalated compound with a 14.0A spa- cing appeared. After it was replaced by water, a characteristic 8.35A base spacing of nacrite hydrate intercalate was formed. Under the condition of normal atmosphere, the nacrite hydrate was stable. However, when the nacrite hydrate was placed in an atmosphere with saturated ethylene glycol, the nac- rite hydrate was destroyed rapidly. This demonstrates that Fangjiashan kao- lin is a nacrite-bearing kaolin deposit. Further"n.ore, IR and intercalation technique also show that the aacrite mineral exists in a form of coarser fraction larger than 2 um and the domain of kaolinite decreases with the increase in that of nacrite. This may indicate that nacrite was formed thro- ugh reconstruction of kaolinite under geological structural stress. The nacrite- bearing kaolin deposit is only seen, in the vicinity of the Jiangshan-Shao- xing deep fault, along the transitional zone of two geological units, suggesting that the movement of the Jiangshan-Shaoxing deep fault might have con- tinued to the Hercynian period or even to the Yanshanian period. It is the compression and compresso-shearing of the fault that provided the pressure for the formation of nacrite in this area.