Granitic rocks in South Korea are mainly Jurassic and Cretaceous. The amphibole chemistry exhibits the predominance of edenite- and tschermakite-type coupled substitutions for both Jurassic and Cretaceous granitic rocks in South Korea. It is also suggested that glaucophane-, riebeckite-, and richterite-type substitutions may not be present. A little larger component of tschermakite-type substitution is indicated by the data points for the Jurassic amphiboles.

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Six mineral belts, extending roughly north-south and being related to certain lithologic types, are recognized and delineated in the Union of Myanmar. These are: (1) Tin-tungsten belt of the Tenasserim region, southwestern Kayah State and the western marginal zone of Shan State; (2) Antimony belt of parts of Shan, Kayah and Mon states; (3) Lead-zinc-silver-barite belt of western Shan State; (4) Porphyry copper belt of Monywa and Wuntho areas' (Central Myanmar); (5) Nickel-chromium belt of northern Chin Hills; (6) Oil-gas belt of Central Myanmar, Irrawady Delta and its off-shore area (Gulf of Mataban). Of these, the antimony belt, having a sporadic distribution, is poorly defined and delineated. At least ten mineral epochs with sixteen separate or related mineral events are proposed : (1) Late Precambrian (Pb-Zn-Ag, Au); (2) Late Cambrian (Pb-Zn-Ag, Ba); (3) Late Ordovician (Pb-Zn-Ag, Ba); (4) Late Carboniferous (Sb); (5) Permo-Triassic (Fe); (6) Cretaceous, Jurassic and possibly Triassic (Sn-W); (7) Cretaceous-Eocene (Cr-Ni, jadeite, Au); (8) Mio-Pliocene (oil-gas); (9) Middle Tertiary? (gemstones); and (10) Pliocene (Mn, Cu). Also briefly discussed is the status of economic minerals of Myanmar.

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Seventy-nine submarine volcanic rocks collected from the volcanic front of the Izu-Ogasaara (Bonin) Arc and the northern Mariana Arc were analyzed for Au by atomic absorption spectrometry using a graphite furnace atomizer after solvent extraction separation. The Au content varies from 0.1 to 6.1 ppb with an average of 1.5±1.2 ppb(n=79). The content of Au tends to decrease with increasing silica content because the average Au values for the basalts, andesites and dacitesrhyolites were 2.0 ppb(n=38), 1.2 ppb(n=29) and 0.48 ppb(n=12), respectively. As for the other elements, Au is positively correlated(r>0.5) withCu, V, Co and Mg; The Au and K2O in the tholeiitic rock series are correlated, positively on the samples with low K2O (ca.0.6 %) contents. Those with high K2O contents, however, appear to have a negative correlation. The Au content of the studied volcanic rocks is more or less similar to common marine sediments. Whereas, the sediments related to the hydrothermal activity are much dominant in Au. The ocean floor ferromanganese oxides are less enriched in Au, reflecting oxygen-dominant marine environments.

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Morphology and grain size of chalcopyrite in the intimate associations of sphalerite-chalcopyrite including the chalcopyrite emulsion and "chalcopyrite disease" were carefully checked, based on microscopic observations of natural ores and on annealing experiments using synthetic Cu-Fe-bearing sphalerite solid solutions. Ore specimens from several Japanese deposits clearly show that chalcopyrite emulsions with larger grain sizes are included in Fe-rich sphalerite coexisting with pyrrhotite, and the emulsion texture is limited to relatively old deposits. The results of the annealing experiments for the Cu-Fe-bearing sphalerite samples synthesized at 800°C show that the habit of isocubanite or chalcopyrite as an exsolved phase is lamellar in Fe-rich sphalerite and lenslike to irregular bleblike in Fe-poor sphalerite, depending on FeS content of the host sphalerite. This feature would be applicable to sphalerite-chalcopyrite associations attributed to replacement reaction, because FeS in sphalerite is consumed to form isocubanite or chalcopyrite. Thus in the case of the sphaleritechalcopyrite associations by the diffusion-controlled growth, morphology and crystal size of chalcopyrite are controlled mainly by both FeS content of host sphalerite and kinetic effects.

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We have employed two types of epoxy-resins mixed with carbon powder in mounting mineral grains for electron probe micro analyses. On metalic mineral grains such as a Pt-Fe alloy mounted on the resin with no carbon coating on the surface, we have made electron microprobe observations and analyses. The results show that the resin has enough conductivity to make the analyses without the coating. Thus, this method gives efficient way to treat many specimens.

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