Propylite of Miocene epoch, host rock of the Pb-Zn vein of Toyoha Mine, is characterized by the presence of chlorite, calcite and albite. This rock was studied petrographically as well as chemically and it was clarified that this rock belongs to calc-alkali rock series.
Based on the mineral assemblages, and the relative abundance of the minerals the alteration halo around the Tajima vein of this mine is divided into the following four zones of altered rock facies from outer zone to inner one:
(a) Calcite-chlorite-albite
(b) Calcite-sericite-chlorite-quartz
(c) Calcite-chlorite-sericite-quartz
(d) Quartz-sericite-pyrite
The chlorite to sericite ratio in facies (b) is higher than that in facies (c), then these two facies are distinguishable. The zones of facies (b), (c), and (d) develop in both sides of the ore vein, while the distribution of the facies (a) is regional. The rocks of four altered rock facies were chemically examined and the following results were obtained:
1) Facies (a) is compositionally characterized by the presence of aboundant H₂O compared with unaltered propylite.
2) In the zones of the facies (b) and (c), migration of various kinds of rock forming elements is remarkable though the original rock fabrics have been kept.
3) The zone of facies (d) is distinguishable from the preceding three zones in notable addition of SiO₂, FeS₂ and alkalis.
It seems to the authors that the facies (a) alteration played a role of harbinger for the alteration around the ore vein. Facies (b) and (c) are gradational alteration zones perhaps formed by the reaction between ore forming fluid and wall rock. Facies (d) is a zone so intensely affected by the ore forming fluid that original rock fabrics were obliterated.

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Beryl ores of Egypt occur in two geologic environments. In the first environment, beryl occurs in micaceous rocks and other schistose rocks in close proximity to contacts with psammitic gneiss. Their spatial distribution depicts their alignment in a fairly well defined zone of an approximate NW-SE trend extend-ing about 45 km. This zone coincides with one of the "deep-seated tectonic zones" in the south Eastern Desert of Egypt, which is characterized by anomalous radioactivity and intense metamorphism, as well as metasomatism and mineralization, caused by acidic intrusions. In the second geologic environment, beryl occurs in pegmatite veins, pegmatoidal lenses and veins, and in disseminated form in orthoclase-rich pink granite. This represents new foci for beryl mineralization which should be tested.

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The Fuke mine, situated at about 10 km north of Okuchi city in Kagoshima Prefecture, is one of the gold-silver ore deposits of the epithermal vein type in the Green-tuff region. The ore deposit is considered to be an intermediate type between the gold-silver vein and the base metal vein.
The high grade ore in the mine is named "Tozi-kin" in which can be visually recognized the part where fine-grained golds are concentrated. As for the electrum in this ore, mode of occurrence and chemical composition have been investigated by a microscope and EPMA. The results are as follows : 1. The Tozi-kin ore often shows a characteristic banded arrangement from the wall rock to the inner of the ore; Fe-Mg chlorite, drusy quartz with pyrite and hematite, fine-grained quartz with banded sulfides and electrum, and green clay mainly composed of chlorite-saponite mixed-layer.
2. Paragenetic sequence of vein minerals may be divided into four stages; First stage: Drusy quartz accompanied by pyrite and hematite. Second stage: Fine-grained quartz characterized by sulfides and electrum. Third stage: Altered minerals. Fourth stage: Barren quartz associated with calcite. 3. Observed ore minerals are electrum, galena, sphalerite, chalcopyrite, pyrite, hematite, hessite, and an unkown Ag-Au telluride.
4. Electrum precipitated after the precipitation of sulfides in the second stage.
5. The electrum filling intergranular cavities of quartz is irregular and angular in shape, whereas that in sulfides varies from granular to cylindrical, and often amoebic.
6. The grain size of electrum is generally less than 50 microns in diameter, but it attains 200 microns in some cases.
7. The chemical composition of electrum from the Fuke-honpi vein shows a very little fluctuation among grains as well as in a grain, with an average chemical composition Ag 19.1 wt.%, Au 80.6 wt.%.
Some of these properties of electrum such as the homogenity of composition and the relatively coarse grains, are considerably different from those of electrum in the Kuroko ore.

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Mineralogical studies of banded iron formation (BIF) of the Dales Gorge Member were undertaken in this paper. The sequence of mineral developments during burial metamorphism was determined under microscope from mineral relationships within BIF through the member. The sequence is shown in Fig. 14. Final stage (Stage IV, in Fig. 14) gives present mineral assemblages observed in BIF, but all minerals in the stage are not simultaneously associated together (see text). The assemblages are usually formed on the basis of an assemblage, quartz-hematite-magnetite-siderite, although siderite is in places distributed sparsely in amount. Most of minerals seem to have developed on the process of increasing in the reducing potential with increasing metamorphic grade. Pyrrhotite indicates that carbonaceous matters gave the reducing environment. Minnesotaite and stilpnomelane in the earlier stage seem to have been continuously stable, or seem to have responded to reactions of substitution and reduction as Mg²⁺ Fe₂₊and Fe³⁺→Fe₂₊during metamorphism. The occurrence of quartz veinlets (10μ to 3 mm in width)shows that other metallic elements than K and Na were little mobile during metamorphism. The chemical composition in each mesoband, except fluids (H₂O, CO₂, etc), K, and Na, appears to reflect the primary precipitation of BIF.

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