The characteristics of supergene zoning and processes of oxidation of disulfide-rich ore deposits in Lower Yangtze area, Southeast China, are representative to the warm and humid area in medium latitude zone. The distinguishing features are (1) limonite^*1 gossans extended to a great depth due to the slow uplift of the area during the long process of oxidation; (2) the existence of a subzone of current secondary sulfide enrichment due to the rapid decomposition of Cu sulfide ore in the upper part, which makes Cu intensively migrating downward; (3) the assemblage of secondary native copper, cuprite and their further oxidized products, tenorite and malachite, is an evidence of the ever-existence of ancient secondary sulfide enrichment; (4) carbonate and silicate are the prominant oxidation products of Pb-Zn ore deposits.
The contrasts of the characteristics of sulfide ore oxidation in Lower Yangtze area to that of the arid Northwest China are also clarified in this paper.

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Relative abundances of a number of chemical elements have carefully been evaluated for several individual kuroko deposits from Shakanai and some other mines in Akita area. On the basis of the data obtained, an attempt has been made to verify from a geochemical point of view the recently proposed hypothesis that the kuroko deposits were originated primarily from the mean settling-flux of biogenic entities in the ocean, i.e, from the PUMOS (KAJIWARA, 1982 b, c, 1983a, b, c; KAJIWARA and TONG, 1983).
As compared with the PUMOS, the kuroko deposits are in general characterized by the enrichment of a group of metallic elements (Zn, Cu, Pb, As, Sb, Bi, Cd, Ag, In and Au) and also by the depletion of another group of metallic elements (Fe, Mn, Ba, Ni, Co, Ga, Mo, W, Ge and Hg) and other common rock-forming elements (Si, Al, Ca, Mg, Na and K). It is worth noting that the relative mode of abundance of metallic elements enriched in the kuroko deposits is fairly analogous to what is predicted for the PUMOS (see Fig. 2 in the text). Strictly to say, however, the individual deposits are never uniform in chemical composition. Giving attention to some important ore elements (Fe, Ba, Zn, Cu, Pb, Ag and Au), the deposits are found to constitute a remarkable chemical differentiation series which is characterized by the uniquely-defined trend originating from the composition of PUMOS (see Figs. 3 to 7 in the text). This "kuroko differentiation series" appears to be most likely due to fractional removal of the elements from the PUMOS, i.e., Fe>Ba>Cu>Zn>Pb = Ag = Au in the order of magnitude.
The concept of "diagenetic chemical differentiation" is proposed to account for the observed geochemical characteristics of the kuroko deposits. Our conclusions may be summarized as follows: (1) The kuroko deposits were derived primarily from the PUMOS (or at least suchlike chemically equivalent to it).
(2) Things started with the proto-kuroko formation, which can be defined as a series of diagenetic decomposition processes of the PUMOS under anoxic or euxinic submarine environments (i.e., oxidation decomposition of organic matters by seawater sulfate=seawater sulfate reduction by the organic matters) (KAJIWARA, 1982c, 1983a).
(3) Significant fractionation of elements took place during the proto-kuroko formation. Some environmental controls such as "redox control" (see Fig. 8 in the text) and "organic acid control" (see Figs. 9 and 10 in the text) are considered to have been responsible for the removal of a number of elements which are almost missing in the present kuroko deposits. Metallic elements enriched in the present kuroko deposits should be regarded as the residual ones left behind at the given organogeochemical environments.
(4) The proto-kuroko deposits thus formed have further undergone significant chemical modifications through their subsequent pre-and post-burial diagenetic processes to result the "kuroko differentiation series". A series of phase-transformations of ore minerals (especially as to Fe and Cu minerals) are suggested to have taken place during a certain stage (probably very early stage) of the sebsequent diagenetic processes. It appears that some of important ore minerals such as pyrite and chalcopyrite are essentially of diagenetic origin. Fe and Cu are assumed to have been fixed initially as their individual mono-sulfide phases.
(5) Taking into consideration the possible diagenetic phase-transformations of ore minerals, it maybe concluded that the "kuroko differentiation series" is due to a sort of "mineral solubility control" (see Fig. 12 in the text), i.e., fractional decomposition or dissociation of the minerals involved, during the diagenetic history.

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Skarns of the Kamioka mine (Tochibora and Maruyama deposits) are studied with special reference on the occurrence of garnet skarn. Skarn garnet of the Kamioka mine has been, so far, classified into two types; M-garnet that is skarn mineral of M-skarn mineralized during the migmatitization of Hida metamorphism and H-garnet that is alteration product of hedenbergite skarn disseminating sphalerite and galena (called "Mokuji ore"). Besides these two types of garnet, garnet is observed to make garnet skarn zone associated with hedenbergite skarn, and called E-garnet in this paper.
E-garnet associates with epidote and quartz in garnet skarn, and its original rock is Inishi migmatite or M-skarn, then it is important to discriminate it from relict M-garnet that remained in epidote skarn. E-garnet is characterized by higher iron content than M-garnet.
Garnet skarn composed of E-garnet is mainly distributed in the NE-SW direction along the Shikama valley between Tochibora and Maruyama deposits. Depositional condition of garnet skarn is estimated as temperature 450-320°C and X_CO2 less than 0.1 by phisicochemical consideration.

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The Akenobe mine is composed of xenothermal polymetallic veins, genetically related to Late Cretaceous or Early Tertiary granitic activity. The deposit indicates the characteristic zonal distribution of minerals from the mineralization centre outward: (1) tin-tungsten zone, (2) tin-copper zone, (3) copper-zinc zone, (4) zinc-lead zone, (5) silver zone. The succession of mineralization or paragenesis is generally same as this order. The geochemical environment of the mineralization would change towards low f_s2-f_o2 conditions, as the temperature dropped.

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Chromite is an ore mineral possessing the highest hardness (VHN) and very low reflectivity among the common ore minerals. Though the ideal chemical formula of chromite is given by R²⁺OR³⁺₂O₃, chromites in nature show a noticeable substitution variation between chromium and aluminium trioxides.
It is thought that the degree of substitution variation is reflected on reflectivity or hardness of the mineral. Therefore, EPMA analysis for the collected chromites were carried out first. For this study Leitz MPV Compact Microscope Photometer and Leitz Micro-Hardness Tester were used for the reflectance and hardness measurements respectively. Samples of podiform chromites were collected from the Hidaka district, Hokkaido and the Chugoku-Shikoku districts, southwestern Japan, and from the Fethiye mine, southwestern Turkey. Stratiform chromites from the Merensky Reef of Bushveld Intrusion were also provided for this study.
The relationships between chemistry, reflectivity and hardness of chromites were investigated synthetically, and interesting mutual relations among these have been disclosed.

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K-Ar age determinations were carried out on the Jecheon mass and adjacent rocks occurring in the Ogcheon Zone of South Korea. Biotites separated from the Jecheon mass yield ages of 179, 169 and 159 Ma, confirming that the mass and the related molybdenum deposit were formed by the Daebo igneous activity. Muscovite from the Daehwa mine gives an age of 89 Ma and belongs to the Bulgugsa activity.
Muscovite from pegmatite near the Dangdu mine, which intrudes into the Ogcheon Group, gives a Precambrian age of 1720 Ma. Thus the original rocks of the Ogcheon Group appear to have a middle Proterozoic age.

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