The Takatama Mine, located in Fukushima Prefecture is a typical epithermal ore deposit. The deposit consists of nearly one thousand veins. Quartz gangue comprises two-thirds of the veins and adularia gangue the remaining one-third. This mine, the largest gold producing unit in Japan, has in the past thirty-five years produced 1, 690, 000 tons of ore containing 21 tons of gold and 204 tons of silver.
The eight types of vein quartz into which the writer has classified the gangue material appear clearly selective—above the veins, in between and below—in the central portions or extremities —in the bonanzas and in the barren parts.
It was ascertained that the habit, size and fineness of the gold particles and quartz crystals contained in the veins adhere to a formula and can be accurately predicted by the position of the gold in the vein.
Statistical studies made on the habits and textures of the gold and quartz in correlation with their position in the ore veins have proved very helpful in prospecting. From a segment of newly discovered veins at an outcrop or underground it can be determined by such studies, whether these veins would be worth while further prospecting and in case considered so, in which direction the prospecting adits should be driven.
The country rocks of the Takatama deposit were formed by severe and extensive alternation of liparitic tuff and shale by silicification and alkalization (adularization). Only two or three other cases in Japan can be cited of instances where the gangue minerals contain a high percentage of adularia. The adularization of the country rock is a type of alteration rather uncommon in Japan.
From the results of a detailed survey and observation of both types of alterations, it can almost no longer be said that the country rock alteration was the result of infiltration of the mineral solutions through both walls of the fissures at the time of ore formation. In the writer's opinion the excessive siliceous solutions, barren in nobles, ascended before the mineral solutions and first silicified to a high degree the coarse textured rocks. Immediately after both types of alteration were completed, the residue, namely the mineral solutions bearing gold and silver ascended, depositing many gold and silver bearing ore veins in the alkalized areas. The highly silicified country rock is found extensively on the summits of hills as cap rock. Alkalization took place below this area where silicification was weaker.

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Bornite normally appears homogeneous under a reflexion microscope at the magnification of 1, 000 times. However, upon heating at 100°C to 450°C bornite will show, always, chalcopyrite segregations in the shape of small lattices, lamellae emulsions and lenses or cells. Such microstructures of bornite chalcopyrite intergrowths strongly resemble the sc-called exsolution texture frequently found in natural ores. To shed light on this phenomenon, samples of bornite produced at the mines enumerated in Table 1 were crushed to granules of about 150 cubic millimeter, sealed hermetically in pyrex glass tubes, and heated at a rising temperature rate of 10°C per hour until within the range of 100°C to 500°C, then they were quenched. Upon examination of these heated products, the following observations were made.
(1) The functional relationship observable between the quantity of segregated chalcopyrite and the temperature differed according to the origin of the ores. The differences were in quantity segregated, temperature of segregation, and temperature of disappearance.
(2) The texture of chalcopyrite appearing in the bornite samples from Yakuwa Mine went through the following transitions : a) at about 130°C, fine chalcopyrite lattices began to appear all over the ore particle, b) the lattices decreased in number and increased in size with the rise in temperature, c) the total quantity of segregated chalcopyrite gradually increased and formed lamellar, tense-like and emulsive textures in addition to the lattices, d) at temperatures higher than 320°C, the segregated chalcopyite began to decrease, the texture being reduced to some lenses and emulsions, which also disappeared in the final stage at 450°C. In the bornite from Sangasho and Sakurago Mines only a small quantity of chalcopyrite segregated upon heating, and the change in texture was limited to the formation of some lens-shaped or emulsive segregations.
(3) The results of chemical analyses of the samples used are given in Table 2 (Items (1, 4, 7 and 10)).By subtracting the value for the impurities computed by Rosiwal′ s method from the analytic value the ore samples were found to contain 3, 5, 10 and 15 mol% of chalcopyrite respectively. These values were collated with the quantity of segregated chalcopyite and found to be in an approximately direct ratio with the latter, as illustrated in Figure 4.
(4) X-ray photographs of the samples from Yakuwa and Sakurago Mines showed the following phenomena : a) Debye-Scherer's lines due to chalcopyrite as well as to bornite were presented even when the samples were at room temperature. b.) when the sapmles were heated and the maximum chalcopyrite segregation was effected the lines increased their intensity, c) when the temperature was rised at 400°C to 450°C only Debey-Scherer′s lines due to bornite were observed.

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The "Sorachi Anticline" lies between the Akabira and Mojiri coal mines, Ishikari Province, Hokkaido. The basement structure is an embryonic anticline which was formed after deposition of Cretaceous formations. A second anticline occurs in the stages of coal seams which belong to Wakkanabe and Bibai coal-bearing formations. The axis of the embroyonic anticline nearly coincides with the second anticline. Both anticlines remained through periods of coal deposition of the Ishikari Series. In two stages of coal deposition, coal seams are often interpreted as composite by interpolation of bands or partings of sandstone and shale. The partings gradually increase in thickness towards east or west from the axis, so that the subordinate seams of coal become separate from each other. The main cause of the splitting of the thick seams of the anticlinal axis into a number of progressively thinner seams away from the axis is differential subsidence that has taken place in the Sorachi Coal Field.

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