The review is the explanation on the technical method of the improvement of chrome pollution places. Chrome slag which was a waste of manufacturing of sodium bichromate from chrome iron are was almost used for filling up arround plants or sea coasts, etc. before 1970. The slag, however, brought about the public nuisance problem in Tokyo and Hokkaido in 1973 by exuding of yellow sodium chromate solution into underground water. Especially, the pollution in Tokyo became a big social problem on account of filling up in city area. Accordingly, Tokyo city office organized a technical committee for the improvement of the contamination place and have discussed the counterplan. The committee investigated the environmental pollution around contamination places, the influences for living body and the prevention of environmental pollution, and announced the conclusion at October, 1977.
The development and the method of the improvement of contamination places were explained here. It is being watched with keen interest that montmorillonite and zeolite are used for making the contamination place harmless. Namely, Cr³⁺ is exchanged by positive ions in montmorillonite and zeolite and its fixed in crystal structures, after Cr (VI) which exuded from chrome slag is reduced Cr (III) by using both the immidiateeffective reducing agent, for example ferrous sulfate and the slow-effective reducing agent, for example lignite. Moreover the technical works which make contamination places harmless was explained.

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Mineralogical problems concerned with the genesis of kaolin minerals in sedimentary kaolin deposits and related sediments around Nagoya are reviewed. The kaolin deposits are mainly composed of platy kaolinite, whereas the basement granite has been weath-ered mainly to long tubular halloysite. Pyroclastics intercalated with the kaolin deposits and the overlying sediments were altered into spheroidal halloysite or a mixture of spheroidal halloysite and platy kaolinite. The genesis of these different kaolin minerals is discussed with reference to the variation in degree of disorder of halloysite.

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Kaolin clays produced in Japan is classified into refractory-clay and kaolin. And the former, moreover, is divided into shale-clay, Kibushi-clay, Gaerome-clay and hydrothermal refractory-clay. Among these kaolin clays, Kibushi-and Gaerome-clays are most important and their output exceeds 60% of that of all kaolin clays.
Genetically, they are divided as follows; hydrothermal, residual, sedimentary and diagenetic. Particularly, sedimentary type deposits are the most predominant and hydrothermal type ones next to it.
Hydrothermal clay deposits are distributed being confined to both the late-Cretaceous acid volcanic zone and the Miocene-Pleistocene volcanic zone. Kaolin, pyrophylliteand sericite clays occur in these deposits with close relation to each other. Three deposits, Itaya, Hiraki and Omura mines, are very outstanding as kaolin clay deposits. But most of them show very complicated occurrence controlled by various geologic features andare rather small in scale.
Sedimentary kaolin clay deposits, which comprise shale-clay, Kibushi-clay and Gaerome-clay, occur in the Palaeogene and the Pliocene coal-or lignite-bearing formations. It is very characteristic that they always occur in the basal parts of these formations. Chemical features of these clays indicate Pliocene was more favorable age in climatic condition for formation of kaolinic weathering crust.
However, supply of kaolin clays does not meet the demands in Japan. About 50% of kaolin, which is used mainly for paper and porcelain, is imported from the United States and other countries. The output of refractory clays has increased steadily. But the results of analysis of production statistics suggest some of refractory-clays, particularly Kibushi-clay, will be exhausted in near future.

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Clay has played an important role in the refractories industry because of its special properties such as favorable plasticity, good sinterability and low cost. An outline of fire clay refractories and the features of clays are mentioned in this paper.
The principal chemical composition of clays is silica, alumina and water, and these consist mineralogically of kaoline mineral and quartz. Clays also contain impurities, for example iron oxide, potassium oxide, and sodium oxide, and therefore also contain feldspar, sericite and pyrophyllite.
In industrial ceramics, clays are used two ways. One way is the dead burning of clays which is used for large grog or refractory grain particles in fire clay refractories. The process requires special properties such as high density and high temperature stability. In the second way, clays are used for binder for which it is necessary to have favorable plasticity.
Fire clay refractories are composed of refractory grain particles of burned clay and binder clay, their properties are decided by the raw materials and heat treatment used.
The chemical composition of fire clay refractories are silica, alumina and accessary components which are the same as clays, and these mineralogically consist of mullite, cristobalite and a glass phase.
This fact suggests that the kinds and quantity of impurity contained in the formation of cristobalite give a marked effect on the shrinkage, tightening and the spalling of a ceramic body.
Damage in fire clay refractories can be observed during service in the following cases; 1) presence of impurities which cause the formation of glass, 2) thermal expansion spalling due to the presence of cristobalite, 3) alkali attack in the blast furnace, 4) bloating phenomena in the ladle.

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