韓国のジュラ紀および白亜紀の花崗岩類の角閃石の化学組成をエネルギー分散型蛍光X線分析装置(EDS)を用いて定量した.この分析値を検討した結果,これらの角閃石族の組成はエデン閃石型とツエルマク閃石型対置換の組み合せ置換が卓越していることが判明した.また,ラン閃石型,リーベック閃石型とリヒテル閃石型の対置換はほとんどみられない.ジュラ紀の角閃石族にツエルマク閃石型の対置換が白亜紀のものより若干卓越していると考えられる.

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ミャンマー連邦では, ほぼ南北にのびた各岩相タイプに関連した以下の6つの鉱化帯が認められる :
(1)Sn-W帯=Tenasserim地域, Kayah州南西部, Shan州西縁部; (2)Sb帯=Shan州, KayahおよびMon州の一部; (3)Pb-Zn-Ag-BaSO₄帯=Shan州西部地域; (4)斑岩銅帯=MonywaおよびWutho地域(ミャンマー中央部); (5)Ni-Cr-帯=北部Chin Hills地域; (6)石油-天然ガス帯=ミャンマー中央部から南方のIrrawadyzデルタおよびその沖合(Martaban湾)にかけての地域, これらのうち,Sb帯だけは, その分布が散発的で鉱化帯として明確には定義しがたい。 現在, 以下の少なくとも10ヶの鉱床生成期を設けることができる : (1)先カンブリア時代=Pb-Zn-Ag, Au ; (2)カンブリア紀後期=Pb-Zn-Ag, BaSO₄ ; (3)オルドビス紀=Pb-Zn-Ag,BaSO₄ ; (4)石炭紀後期=Sb ; (5)二畳－三畳紀=Sn-W ; (6)白亜, ジュラ紀, 恐らく三畳紀=Sn-W ; (7)白亜紀-始新世=Cr-Ni, ヒスイ,Au ; (8)中新-鮮新世=石油, 天然ガス ; (9)第三紀中期(?)=宝石類 ; (10)鮮新世=Mn, Cu(+Au). また, ミャンマー連邦において経済的に重要な鉱物資源の現状についても, 簡単に述べる。

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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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