高岭石-多水高岭石矿物晶体形态与演化

通过对我国南方许多风化型高岭土矿床研究查明,在表生条件下形成高岭石-多水高岭石矿物的基本因素是决定于风化母岩的岩性和水介质的物化性质。水介质的物化性质又明显地受到风化母岩的岩性类型和结构构造、动力裂隙的发育程度、围岩的稳定性和透水性、气候、地形地貌和植被等因素的综合性制约。

MORPHOLOGY OF THE CRYSTALS OF KAOLINITE-HALLOYSITE MINERALS AND ITS EVOLUTION

The weathering-type of kaolines consist of kaolinite-halloysite minerals.The members of this type of minerals exhibit some regularity in their distribution in the sections of weathered crust.A well-preserved weathered crust of kaoline can be divided into the three zones,i.e.completely-weathered,incompletely-weathered and semi-weathered zones.The completely-weathered zone consists mainly of 10Å halloysites,being from tubular to elongated platy crystals.The incompletely-weathered zone consists mainly of 7Å and/or 10Å halloysites,being developed on the basis of crystallite-kaolinite,and formed spheric or elongated platy crystals in the initial stage of crystallization.The semi-weathered zone consists mainly of crystallite-kaolinites,forming an irregular platy aggregate of very fine crystals and preserving fairly well the outlines of minerals.This regularity in the distribution and evolution of minerals was a result of different stages of weathered crust evolution.The author concludes that the kaolinite-halloysite minerals can be regarded as a aeries of minerals formed in the process of their evolution.The separate members of this series are genetically in close relation and are composed essentially of identical crystal structural units,the kaolinite layer units.The difference between them lies in the presence and amount of the interlayer water.It is the interlayer water which caused the displacement of kaolinite units parallel to layer and hence led to the disorder in crystal structures.However,the molecular water between the kaolinite layers is not stable.When it is expelled,the superimposition in the direction of c-axis between kaolinite layer units will return to the normal pattern.Consequently,the tubular halloysite changed to hexagonal kaolinite.The common members of kaolinite-halloysite minerals are crystallite-kaolinite,kaolinite,7Å halloysite and 10Å halloysite.In literatures crystallite-kaolinite was called poorly-crystallizing kaolinite,which may be confused with the fireclay.The so-called crystallite-kaolinite is the product of initial crystalline state.Its crystal form is usually incomplete and its grain is extremely fine.It was formed in the initial stage of weathering.The nomenclature of the 7Å halloysite is still a controversial issue at present.The author holds that the 7Å halloysite does exist in the nature and it represents the product of some weathering stage.