The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists

Thermal study of bornite

Tsunehiko Takeuchi, Matsuo Nambu

1952 Volume 36 Issue 2 Pages 33-42
Published: May 20, 1952
Released on J-STAGE: March 18, 2008

DOIhttps://doi.org/10.2465/ganko1941.36.33

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Mineralogical changes of bornite by heating in nitrogen atmosphere are studied microscopically. Eornite specimens of about, 3mm diameter, but a few percents of chalcocite. are associated microscopically, are heated for an hour at every temperature between 50°C to 1, 000°C and are observed under the microscope.
The results obtained are as follows:
(1) At.80° ?? 150°C, margin of the chalcocite grains enclosed in bc ?? nite is altered to digenite but above 160°C the mineral is diffused into chalcocite.
(2) Between 190° ?? 650°C, chalcocite diffused into an homogcneous bornite solid solution, bu ?? by slow cooling, chalcocite is reappeared as several inmixing textures.
(3) From 190° to 430°C, minute crystals of chalcopyrite and tetral ?? edrite showing emulsion, wedge-like of globular forms are newly segregated from bornite solid solution. Relation between heating temperatures and segregated amounts of the minerals is shown in Figs. 3 and 4.
As shown in the Table of chemical composition of the sample, the bornite has, some excess chalcopyrite and tetrahedrite components and excess ones are segregated at above temperatures.
(4) A desulphuration curve is. given in Fig. 1-A. As the desulphu ?? ation at 400° ?? 450°C may be explained by that of chalcopyite impurity, the curve of the pure bornite also be considered as Fig. 1-C.
(5) At above. 650°C, some part of the bornite is dissociated to FeS and Cu₂S. Microscopically, two kinds of the texture can be seen as shown in Fig.5 (below 730°C) and Fig. 6 (above 730°C)
(6) Drop-like or veinlet metallic copper is appeared at above 500°C and veinlet pyrrhotite is appeared at above 950°C.

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Eclogitic rock found as a block on the River Yoshino, Shikoku

Toshio Ishikawa

1952 Volume 36 Issue 2 Pages 42-46
Published: May 20, 1952
Released on J-STAGE: March 18, 2008

DOIhttps://doi.org/10.2465/ganko1941.36.42

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The author described the petrographical character of the eclogitic rock found as a block on the River Yoshino, and gave some consideration on its genesis.

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Geometrical consideration on the construction of geological maps (I)

Rational construction of formation boundaries (1)

Yushi Funayama

1952 Volume 36 Issue 2 Pages 47-59
Published: May 20, 1952
Released on J-STAGE: March 18, 2008

DOIhttps://doi.org/10.2465/ganko1941.36.47

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Geological maps are very important not only for the basis of geology, but also for the studies of stratigraphy and fuel deposits, especially in explorating and developing coal-fields or oil-fields. Therefore, the construction of geological maps should be done with all caution. And yet, conventicnal methods of mapping have some errors and so unreasonable, because of no consideration on the types of folding which the strata for ?? according to their natures.
Here the writer proposes the rational methods for (1) tangent method, (2) hypotenuse method and (3) combination method, geometrically considering the types of folding.

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On the Mesozoic tuffaceous rocks in Kammon District (II)

Yoshio, Ohji

1952 Volume 36 Issue 2 Pages 59-64
Published: May 20, 1952
Released on J-STAGE: March 18, 2008

DOIhttps://doi.org/10.2465/ganko1941.36.59

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The Mesozoic red and green rocks, distributed in the southern district of Kokura and Yahata City, are belonged to the Kammon group and are subdivided into two subgroups; Wakino (lower beds, narrowly spreaded) and Shimonoseki (upper, wide).
His geological, microscopical and chemical analytical observations on these rocks suggest the next results as followed; 1, Difference between above two subgroups is not largely expressed. Almost of these rocks show the socalled common clastic structure and corresponds the resemble rocks in Moji district. 2, But they are tuffaceous rocks or tuffite on the point of bearing plenty andestic rock fragments, etc. On other words, they have some relation with igneous action.
3, Also, discussing from the view of igneous action, the authour emphasizes to pay attention into the socalled Yahata beds.
4, After all, these red and green rocks in this district are tuffaceous and partly normal sedimentary, and play a more large parts as the key beds for Mesozoic group than as igneous action.
5, Genetic explain on red and green color of these rocks is not yet enough.

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