Some Ni-Fe-Co arsenides and sulpharsenides except for arsenopyrite associated with calcic Fe-W skarn deposits of the Ulsan mine, Republic of Korea, have been investigated by means mainly of ore microscopy and electron microprobe analysis. These minerals involve niccolite, rammelsbergite, lollingite, gersdorffite and cobaltite, and are usually minor or trace in amounts except for lollingite which represents a subordinate constituent of the concentrates of arsenic ore (arsenopyrite ore) coming from the mill plant.
In this paper, the mode of occurrence and mineralogical properties (mainly optical and chemical data) for these minerals are given. It is also suggested that the source of nickel and cobalt in these minerals may be attributed to the nearby ultramafic rocks (partly serpentinized dunite and harzburgite) constituting the basement of the Cretaceous volcano-sedimentary piles in the Gyeongsang Basin.

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The mineral deposits of the Hitachi mine are divided into two groups, Fujimi and Fudotaki, according to their stratigraphical position: the deposits of the Fujimi group occurring between lower acidic and upper basic schists and those of the Fudotaki group in a thick pile of the basic schists. Chemical natures of sulfides and ores were compared between the deposits of two groups, mainly between the Fujimi and Fudotaki deposits.
Cobalt and nickel contents of pyrite are higher in the Fudotaki deposits than in the Fujimi deposits. Selenium contents and sulfur isotope ratios of pyrite differ also remarkably between these two deposits. Galena is more frequently observed under microscope in the Fujimi ores than in the Fudotaki ores. Barite occurs only in the sphalerite rich ores of the Fujimi deposits and not in the Fudotaki deposits. Such chemical differences of sulfides and ores between the two deposits are attributed to the chemical differences of hydrothermal solutions responsible for the two deposits, not to the physico-chemical differences of mineral deposition.
The observed differences in chemical natures between the two deposits are virtually the same as those between the Besshi type deposits, which are associated with basic schists derived from basaltic volcanics, and the Kuroko type deposits with genetical affinity to felsic volcanics. It is suggested that the hydrothermal solutions responsible for these deposits were once nearly in equilibrium with underlying volcanic rocks (having genetical connection with deposits) in respect to the exchange of chemical constituents.

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Regional lateral zoning of the late Mesozoic to early Tertiary endogenic lead-zinc and copper deposits is known in Japan and Korea. The lead-zinc deposits are distributed on the Japan Sea side and the copper deposits on the Pacific Ocean side of Japan. The lead-zinc deposits occupy the northern half and the copper deposits the southern half of Korea. Sikhote-Alin Province may belong to the lead-zinc zone. According to the latest geological data available, a similar regional lateral zoning of the Mesozoic endogenic lead-zinc and copper deposits is recognizable in the area south of the Yangtze River in China. The lead-zinc deposits occupy the western part and the copper deposits the eastern part of that area. Moreover, a similar tendency toward zoning of ore deposits may be present in Southeast Asia, although the data available are scarce.
Deformation of the continental plate, due to subduction of the oceanic plate during Mesozoic to early Tertiary time may be one of the most important causes of the lateral zoning of ore deposits in the areas cited. As the result of this deformation, fracturing and following generation of magma took place within the continental plate. The lead-zinc and copper deposits were formed in close genetic connection with the granitic magma originating from the more acidic upper portion and the more basic lower portion, respectively, of the continental plate.
Generally speaking, the gentler the inclination of the subduction zone, the broader the copper zone tends to become. The copper zone south of the Yangtze River in China may be one of the best examples of this broadening in East Asia. The zone has a width of more than 500 km. In contrast, in the Burmese-Malayan peninsula, the inclination of the Mesozoic subduction zone may be large; no extensive copper zone is known in that area, and lead-zinc mineralization is poor. Drifting of the Japanese Islands is estimated to have begun about 50 Ma ago.

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the Kosaka mine situated in the northern part of Japan is a typical kuroko deposit mine.
Recently, oxidized ores are found in upper part of black ore, just below the Quaternary sediments in the Uchinotai-Nishi ore body. These ores are mainly composed of barite, quartz, cerussite, and goethite with small amounts of anglesite, galena, sphalerite, and malachite enriched in gold and silver.
With respect to the occurrence and mineral assemblage, four specific types can be distinguished. "A" type is sandy ore which is further subdivided into "A1" and "A2". "A1" is white colored and is composed solely of barite and quartz. "A2" includes a little goethite and cerussite in addition to the minerals of "A1" and has a brown color. The "B" type is characterized by barite, goethite, cerussite and quartz with minor amounts of anglesite and galena. It is a massive and porous ore, containing high amounts of gold and silver. The "C" type consists of barite and cerussite with anglesite, galena and sphalerite and has the highest content of gold and silver. Copper is concentrated as malachite in occasional parts of the "C" type ore. The "D" type is a sericite-rich clayey ore and contains barite, quartz and cerussite.
These ores evidently reveal zonal arrangments both vertically and laterally. In this paper it has been suggested that the ores were formed in situ by the supergene processes of black ore. By use of a Eh-pH diagram, conditions under which respective ore types were formed are inferred.

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Alabandites from Pretertiary bedded- and Tertiary vein-type manganese deposits in Japan have been examined for their sulfur isotopic composition. δ³⁴S (CDT) value ranges widely from -31 to +1.1‰ in 12 specimens taken from 10 bedded type deposits. While the mineral is no more than a minor constituent in most of the deposits, the isotopic features clearly indicate that these alabandites are of bacteriogenic sedimentary origin, thus raising an important constraint for the genesis of this group of deposits. A cluster of δ³⁴S around -30‰ implies an open-system, steady-state reduction (SCHWARCZ and BURNIE, 1973) from a source SO₄^2- with the isotopic level of ca. +20‰. The inferred source is likely to have been in the Triassic sea. Current conjectures upon the age of host sedimentary rocks of the deposits concerned are in favor of this view.
Alabandites from the Tertiary (Miocene) vein type deposits show only a minor variation in δ³⁴S, +4 to +5‰. The data are very similar to the average isotopic composition of sulfides of the Miocene, "Green Tuff", mineralization represented by the kuroko type deposits. The remarkable consistency in sulfur isotopic composition of the Green Tuff mineralization over an extensive area may require a huge, common reservoir of sulfur in some form, which still remains an enigma.

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The Kamioka Pb-Zn deposits are pyrometasomatic and hydrothermal replacements in Hida metamorphic rocks. The ore is divided into two types: The early "Mokuji" ore that is skarn-type ore with hedenbergite and epidote and the later "Shiroji" ore with quartz and calcite. Sericite occurs in the Shiroji ore or as an alteration product in the wall rock of the Shiroji. K-Ar ages of five sericite samples were determined to be 65.3, 65.1, 66.1, 67.5 and 63.8 Ma. The results show that the Shiroji mineralization took place near the end of Cretaceous. The Mokuji mineralization may be not much older than the Shiroji.
Recent finding of metamorphic skarn accompanied by pyrrhotite and sphalerite and crystalline limestone containing primary sphalerite and pyrrhotite suggests that the initial concentration of metals in this area can be traced back to a period prior to the Hida metamorphism. The K-Ar ages of sericites represent the time when the deposits took the present form.

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Two-dimensional frequency distribution of geochemical data was determined by computation of two-dimensional cumulative frequency and its partial differentiation with respect to two variables without any assumption on the type of statistical distribution of data.
The technique was applied to actual geochemical exploration data, which proved the superiority of twodimensional distribution to one-dimensional distribution for defining geochemical anomalies and partitioning a composite population into constituting single populations.
Characteristics of two-dimensional normal distribution and apparent correlation in a composite population were also briefly discussed.

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