Concepts on hypogene mineral zoning, mineral association, mineral paragenesis, and mineralization stage relating to macrostructures of vein filling in ore veins are briefly discussed.
As an example of plutonic ore vein, macrostructures of vein filling of plutonic tungsten-tin-copper vein at the Otani mine, Kyoto Prefecture, Japan, one of representatives of plutonic tungsten-tin veins related genetically to granitoid of Late Cretaceous in the Inner zone of Southwest Japan, are examined. Based on macrostructures of vein filling on the order of ore body, three major mineralization stages, called stage I, stage II, and stage III from earliest to latest, are distinguished by major tectonic breaks. Sequence of mineralization, characteristic features of each mineralization stage, and variations of filling temperature and salinity ranges of fluid inclusions in minerals from stage I to stage III are summarized.

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The Nippo ore deposit, formerly called the Rasa Omine copper deposit, is one of the Kamaishi contact-metasomatic iron and/or copper deposit genetically relating to the Cretaceous granitic activities. Ore minerals of the Nippo deposit consists mainly of chalcopyrite, cubanite, less amounts of pyrrhotite and bornite. The ore contains about 1.0-1.5 grams per ton of Au and 10.0-12.8 grams per ton of Ag.
The writer obtained the native gold and the minerals of the FeAsS-CoAsS-NiAsS and FeAs ₂-CoAs ₂- NiAs ₂ systems, by means of panning of minerals which had been accumulated at the bottom of the classifier in the Nippo mill plant. This mill plant had treated the crude ores from the Nippo ore deposit alone.
The native gold from the Nippo ore deposit are classified into two systems, the Au-Ag, and the Au-Cu-Ag. The gold of the Au-Cu-Ag system is far less in amount than that of the Au-Ag system. The gold of the Au-Ag system ranges in composition from Au ₈₅Ag ₁₅ to Au₆Ag₉₄, and mostly abounds in Ag than Au₅₀Ag₅₀ In the gold of the Au-Cu-Ag system, the minerals of Au ₅₃Cu₄₆Ag (1:1 type cuprous gold) and Au₇₈Cu₁₉Ag₃ (4:1 type cuprous gold) seem to be the stable or metastable phases. Moreover, the lattice intergrowth texture of pinkish gold (cuprous gold) and yellow gold (Ag-poor gold), resulting from the exsolution of the solid solution of these two minerals, can be observable.
The minerals of the FeAsS-CoAsS-NiAsS system from the Nippo ore deposit were divided into two areas, when the composition of minerals was plotted in the ternary diagram of arsenopyrite-cobaltite-gersdorffite (Fe-AsS-CoAsS-NiAsS). However, the following relation is acceptable covering the above two areas:
y=0.60x+0.36
(Correlation coefficient being 0.91, provided that x=As/S and y=Fe+Co+Ni/S)
The Fe-Co-Ni diarsenides from the deposit are of loellingite and Fe-rich safllorite, while Co-rich safflorite and rammelsbergite (pararammelsbergite) are not detected. The ternary Fe-Co-Ni diarsenide compositions fall on the area of the more Fe-rich range (safliorite).
This paper has reported about the chemical compositions of minerals rarely occurring from the Nippo ore deposit, and also some considerations and discussion on the minerals have been given.
Analyses were preformed using the Hitachi Energy-Dispersive Type Electron Microprobe Analyzer, Model-X-560.

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The filling temperature and the salinity of fluid inclusions in minerals from the pyrometasomatic copper-iron and tungsten ore deposits of the Yaguki mine were measured by means of a microscope with heating and freezing stages. The present works aim at the clarification of mineralization relationships between the two kinds of deposits. The results could be summarized as follows:
(1) The ranges of filling temperature of fluid inclusions in quartz, scheelite and epidote from the tungsten deposits are 200°-340°(265°), 220°-330°C(270°C), and 230°-330°C(290°C), respectively (parentheses indicate arithmetical mean values). And the ranges of the salinity of the former two minerals mentioned above are 1.0-2.9 and 2.9-10.5% in NaCl equivalent concentration, respectively.
(2) The range of the filling temperature of fluid inclusions in quartz and calcite from copper-iron deposits is 200°-360°C(291°C), which is almost the same as that of the Akagane mine, Iwate Prefecture. The salinity could not be measured because of a minute inclusion size.
(3) The results of the fluid inclusion study indicate that the mineralization stage of tungsten is later than that of copper-iron. This process of mineralization is supported by the mineral succession and mineral assemblages obtained from the field evidence and the microscopic observation.
(4) The filling temperatures of inclusions from copper-iron ore deposits decreases distinctly toward the upper level, whereas those of inclusions from tungsten ore deposits are confined to a narrow range in spite of the depth.
(5) There is a linear relationship between the filling temperature and the salinity of fluid inclusions in quartz from the tungsten deposits, while scheelite occupies a very narrow area in the diagram of filling temperature vs. salinity of inclusions. From these facts, it is inferred that scheelite crystallized under the condition of narrow ranges of both temperature and salinity.

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The Maruyama Au-Cu-Pb-Zn-W deposit of the Tsumo mine, Shimane Prefecture occurs in massive skarns composed mainly of grandite garnet. At the deposit, tin was incorporated into various minerals during the various phases of skarn and ore formations. (1) First of all, tin went into andradite-rich garnet to form stannian garnet in garnet-wollastonite skarn of the upper to middle part of the deposit. Microprobe line scans indicate that the substitution like 2Fe³⁺ Sn⁴⁺Fe²⁺ could account for the presence of tin. Then, three ways of tin fixation, though their mutual relationships not known, took place. (2) Tin went into silicate to from malayaite associated with green garnet in garnet-wollastonite skarn or with green garnet in the limestone host adjacent to the ores, both being in the upper to middle part of the deposit. (3) Stannoidite-mawsonite assemblage was formed, which is closely associated with bornite and chalcopyrite exclusively in garnet-wollastonite skarn in the lower part of the deposit. (4) Cassiterite-tellurian canfieldite-stannite assemblage was deposited in the altered vein skarn replacing the massive skarns consisting mainly of grossular-rich garnet and clinopyroxene. Pyrrhotite, hessite, native bismuth, and arsenopyrite are characteristically coexiting with the mineral assemblage.
Factors to control the behaviour of tin are considered as follows: higher contents of Fe ³⁺(i.e., higher fO ₂ condition), alkaline environment, and higher temperature (?) could be responsible for (1) ; low contents of Fe and Mg, higher contents of Ca, Sn, and SiO₂ in the fluids, and alkaline environment for (2); increased concentration of Cu and S, higher fS ₂(and higher fO ₂ ?), and lower Ca and SiO₂ contents in the fluids for (3); and acid environment and low fS ₂ and low fO ₂ conditions for (4).
The present study, combined with hydrothermal experiments, suggests a transport mechanism of tin by stannous chloride complexes during ore-forming processes.

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The Fujigatani mine is located about 15 km west of Iwakuni City, Yamaguchi Prefecture. The Mukai-hi Seibu ore body of the mine is a skarn type scheelite deposit and is emplaced at the boundary between Triassic lenticular limestone and slate. The skarns developed in the deposit are classified as Vein skarn and Shelllike skarn on the basis of the mode of occurrences. Scheelite ore, which is accompanied by small amount of pyrrhotite, chalcopyrite and sphalerite, developed in the vicinity of the intersection of both skarns. The vein skarn is about 1 meter in width trending N15°E in the ore body. It shows clear zonal arrangement from marble to its center in the following sequence; (1) marble with carbonaceous material-(2) white marble-(3) brown ferrobustamite zone-(4) white ferrobustamite zone-(5) fine-grained clinopyroxene zone-(6) garnet-clinopyroxene zone-(7) coarse-grained clinopyroxene zone.
Scheelite is deposited within limited zones such as in (5) and (6) of the vein.
Microprobe study reveals the following sudden compositional change of coexisting clinopyroxenes and garnets in the ferrobustamite zones [(3) & (4)]. That is, towards the marble side, ferrous iron content decreases while manganese increases in clinopyroxenes, whereas in garnet ferric iron increases while ferrous iron and manganese decrease. In the same zones, manganese content of ferrobustamite also decreases steeply towards the marble side. Considering this compositional variation in these minerals, it is assumable that environment in the vicinity of marble is in a relatively oxidized condition.
Superiority of reduced skarn is assumed to be caused by carbon in marble and slate. High manganese contents in these minerals of Vein skarn might have been derived from underlying manganiferrous sedimentary rocks.
Taking into account these phenomena, scheelite precipitation in the ore body is presumed to have taken place under environment of relatively low fo ₂ and high fCO₂ conditions.

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The Sakae deposit of the Akagane mine is a pyrometasomatic copper deposit formed along the boundary between limestone and gabbro. At a part of No. 4 orebody in the deposit, were found so-called hightemperature skarns characterized with tilleyite, spurrite and gehlenite. The occurrence of these skarns suggests that they were formed from limestone by the reaction with gabbroic magma, but have suffered intense alteration by the later ore-forming hydrothermal solution related to granitic intrusion. Gehlenite is observed only as pseudomorph, and is completely decomposed to bicchulite with vesuvianite and xanthophyllite. Tilleyite is also partly altered to calcite and foshagite. This occurrence provides a rare example of an overlapping of the ore skarn formation (WATANABE, 1960) with the primary skarn formation (TILLEY, 1951). Chemical composition data on bicchulite, the third occurrence in the world, tilleyite and foshagite, are given with X-ray powder diffraction patterns.

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It is proposed that magnetite-series granitoids represent deep-seated magma reservoirs below an arc volcanism. The northward subduction of Pacific plate may be responsible for Paleogene magnetite-series granitoids in SW Japan and also the fan-shaped opening of the Sea of Japan before 40 Ma. Vein-type molybdenum and skarn-type lead and zinc deposits are genetically related to the granitoids. The change of moving direction of the Pacific plate indicated by the Hawaiian-Emperor bend involved tectonic settings of the Paleogene SW Japan. The outer zone of SW Japan was neutral in tectonic environments after the cessation of subduction from the Nankai trench. A few magmatism on land between 40 and 20 Ma is recognized in the present SW Japan. However, the westward subduction of Pacific plate resulted in the opening of the Shikoku basin from about 30 to 20 Ma. Magma ascended from the upper mantle between volcanic and aseismic fronts in neutral tectonic environments and caused ilmenite-series granitoids associated with volcanic rocks in 13±1 Ma. Tin-tungsten and copper mineralization took place to form vein-and skarn-type deposits. Ilmenite-series granitoids grade northward into monogenic volcanoes composed of magnesian andesite in slightly extensional tectonic environments. Volcanism from basalt to dacite began along the Sea of Japan coast in about 20 Ma and lasted until about 9 Ma. The formation of Kuroko-type deposits is related to dacitic volcanism in 13 Ma. Cooper and gold-silver vein-type deposits may have been formed in the age later than 13 Ma.

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