The Huanzala mine is a copper, lead and zinc mine in Peruuian Andes. The orebodies are bedded or lenticular in shape and occur within several limited stratigraphic horizons of a limestone formation of Cretaceous age. Some intrusive sheets of quartz porphyry (7.5-9.2 m.y.) occur in the vicinity of the ore horizons. On the basis of their mode of occurrence and mineral assemblage, the ores are divided into the following three types, i. e. pyritic ore, skarn ore and "shiroji" ore (argillized ore). They are considered to have been formed by pyritization, skarnization and subsequent hydrothermal replacement processes probably related to the intrusive activities of the quartz porphyry. The mineralization sequence is as follows: pyritization→skarnization with Fe-rich sphalerite mineralization→.galena mineralization followed by chalcopyrite mineralization→"shiroji" alteration with Fe-poor sphalerite mineralization→bornite and, chalcocite mineralization→tennantite mineralization.
It is stressed in this paper that the initial pyritization or the pre-existing pyrite deposit must have played a role of prime importance in a variety of subsequent economic mineralizations. The Pb-Zn mineralization took place within the pyrite deposit to have formed the pyritic economic ores. The pyrite deposit, which has previously been regarded as a barren core of the zonal arrangement of the Huanzala mineralization, should be considered to be the most important target for exploration in this mining area. The quartz porphyry is also important for exploration. It occurs always close to the orebodies, suggesting its intimate genetic relation to the mineralization. The southeastern extension of the Huanzala mining area, which is interposed by the quartz porphyry mass, is suggested to be quite promising for future exploration. On the basis of these exploration strategies, some encouraging results are now being obtained.

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Hyogo prefecture is noted for occurrence of several kaolinic roseki deposits related to the Cretaceous acid volcanics, which are widely distributed through Chugoku province from Hyogo to Yamaguchi prefectures.
The Fukuyama mine, one of them, produces purely kaolinic roseki and quartz-kaolin rocks (siliceous roseki). The former is used for high-grade refractories, and the latter for insecticide carriers. The mode of occurrence of the kaolinic roseki deposit and the genetic relation to the acid volcanisms were investigated.
The area is underlain by rhyolite flow, rhyolitic tuff breccia, dacite intrusive, debris deposits and rhyolitic welded tuff in the ascending order. The roseki deposit mainly occurs in the dacite intrusive and the adjcent rhyolitic tuff breccia, which is possibly explosion breccia. The underlying rhyolite is only weakly altered, and the uppermost welded tuff is almost fresh. The debris deposit consists mostly of variously altered and poorly sorted dacite breccias. It overlies the altered dacite and tuff breccia discordantly.
The purely kaolinic roseki occurs as veins, less than 5 meters in width, in the dacite intrusive, and is accompanied by thin diaspore veinlets at the central part. The roseki is composed mostly of dickite and wellordered kaolinite and accompanied by pyrite dissemination in places. At the outer-side of the roseki veins, the siliceous roseki occurs extensively. It consists mainly of variable ratios of quartz and kaolin minerals occasionally accompanied by mica clay minerals and interstratified mica and expandable minerals. All of the altered rocks are intruded by a felsic dike, which is also more or less altered.
The process of the kaolinization probably has a close relation to a series of local acid-volcanisms as stated below:
(1) Extrusion of rhyolite lava flow.
(2) Deposition of explosive rhyolitic tuff breccia.
(3) Intrusion of dacitic magma near the surface.
(4) Acid hydrothermal alteration mainly in the dacite intrusive and the adjacent tuff breccia, and continuous rising of the dacite intrusive up to the surface to form possibly an altered dacite dome.
(5) Break down of the altered dome to cause the debris deposits, and finally the deposition of the welded tuff, by which the roseke deposits were covered to be preserved.

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When clay minerals are suspended in aqueous solutions containing metal ions, the metals concentrate remarkably to the solid (clay minerals). Using sericite (2M1 muscovite) from the Hikawa mine, Shimane Prefecture, southwest Japan, degrees of the concentration of some heavy metals such as cobalt, copper, zinc, (arsenic), cadmium and lead were examined as functions of the duration of time, metal contents in solutions and pH. A term "suspension pH" is designated in this paper, which represents the pH of sericite-suspension during stirring the suspension. As the amount of sericite in suspension increases, the value of the suspension pH increases until 3 gr. per 100 cc water. The value of the suspension pH coincides well with that of pH of the solution in acid condition (pH<7.0). In alkaline conditions, the suspension pH gradually closes to the abrasion pH as the duration of time increases. However, even after one year duration, the value of the suspension pH does not achieve an equilibrium.
The maximum adsorption of heavy metals in sericite occurs within an hour and as the duration of time increases, the amount of the metal content in sericite decreases. With increasing the contents of metals in solution, the amount of metals in sericite increases to ceratin amount. As the numbers of kind of metal ions in solution increases, the content of each metal decreases keeping the total content of metals in sericite almost constant. Zinc, cobalt and arsenic concentrate more in solid rather in solution, while cadmium and lead remain rather in solution. Experimental techniques affecting the content of heavy metals in sericite such as washing of sericite are examined. Based on the experimental results, considerations on the mechanism of the adsorption of heavy metals, significance of the suspension pH and aging effect of clay minerals in aqueous solution were presented.

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