In the Hanaoka Mine there are more than ten ore bodies, all belonging to the so-called Kuroko deposit (black ore deposit). Results of the writer's studies on this deposit are as follows:
1) As a whole, the ore deposit shows all the characteristics of the Kuroko deposit, but reviewing the individual ore bodies, many of them do not have the characteristics of the Kuroko deposit. The part known to be the Kuroko ore (black complex ore) is not abundant, and is estimated to comprise no more than 1/30 of the volume of the ore bodies as a whole.
2) All of the ore bodies are found at very shallow depth, and oxidation of the ore bodies is not marked, although the action of secondary enrichment is seen even in the deepest part of the known ore bodies. The effect of secondary enrichment is less distinctive on the black ore in the upper part of the ore bodies than on the yellow ore in the lower part of the same ore body.
3) Along the boundary between the ore body and the wall rock different features are seen, depending upon the variation of the characteristics of ores and wall rocks.
4) Silicification took place in all stages of the deposition of various kinds of ores. However, some effects of silicification can probably be attributed to the action which took place after the eruption of liparite.
5) Chloritization of country rocks directly connected with ore deposition is not intense, while extensive chloritization of the liparitic tuff is widely observed in this district.
6) Argillization of the wall rock, and the formation of clay minerals in the ore bodies is very noticeable. The clay minerals vary with their mode of occurrence.
7) The sequence of mineralization is as follows : 1. siliceous ore; 2. yellow ore; 3. black ore. The succession of minerals may be established from the principal ore minerals which compose these ores. The black ore is very complex in mineral association, having-many varieties, and so the succession of ore is considerable in the black ore itself.

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The Asahi mine is located in Kusamoto, Yamakuni Village, in the northwestern part of Oita Prefecture. The ore deposits are narrow epithermal fissure-filling veins related to the eruption of Tertiary apo-andesite. Veins were formed by the successive deposition of coarse-grained ores, carbonate-minerals, fine-grained rich ores and barren ores. The mineralization is characterized by the complex association of sulphide minerals, particularly, argentiferous sulphantimonides. Examination under the microscope makes it possible to recognize two main stages of mineralization in the rich ores :
1st-Sulphide stage. This stage consists mainly of pyrite, sphalerite, chalcopyrite, galena and argentite which were formed together with some polybasite and pyrargyrite.
2nd-Sulphosalt stage. Though some pyrite and chalcopyrite are deposited early in this stage, abundant silver-bearing minerals such as pyrargyrite, tetrahedrite and miargyrite were formed in the later stage.
In each stage, the following sequences of mineralization are noted: (1) sulphides→sulphantimonides and (2) iron→zinc→(copper, lead)→silver→antimony.
From the observation of 520 gold particles on polished sections it is concluded that there are three stages of gold-mineralization in the formation of these gold deposits:
The earliest gold, associated with galena and chalcopyrite, occurs as rounded grains which include more than half of the gold particles. The next stage is represented by the deposition of gold of network-type replacing argentite, and by gold veinlets penetrating polybasite. The last stage is shown as minute inclusions in tetrahedrite and pyrargyrite, comprising only 14 percent of all gold particles. Most of the gold was pre-cipitated in the relatively earlier stage, and deposition of silver was concentrated in the last stage of mineralization.

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The Kishu Mine, about 18km NNW from Shingu, is in the southern part of the Kii peninsula. The principal products of this mine are copper ores and pyrite. The rocks in the vicinity of the mine consist of sandstones and shales of Mesozoic formation and the Tertiary formation called. the "Miyai series", and acidic igneous rocks usually called "Kumano acidic rocks".
The ore deposits of this mine are of shallow vein type and are found along normal faults in the Itaya formation, the upper part of the Miyai series.
On the basis of the rock facies, the Itaya formation may be divided into the following members in descending order:
Member Thickness
G-sandstone …………………………………………………………………150m
F-shale ………………………………………………………………………50m
E-sandstone …………………………………………………………………70m
D-alternation of sandstone and shale ……………………………20-25m
C-sandstone …………………………………………………………………60m
B-shale ………………………………………………………………………50m
A-alternation of sandstone and shale ………………………………… ?
Ore shoots are usually formed in the E-sandstone member as shown in Fig. 5. The favorable openings of the E-sandstone member are due to its own physical properties and also to the relative difference. of the physical characters of each member at the warped fault plane. As a whole, the veins become wider just under the F-shale, which is considered to be the "cap rock" in the formation of the ore veins.
The detailed geologic relation between veins and the persemic garnet-bearing biotite-liparite dike, an off-shoot from the main mass of the Kumano acidic rocks, is also described in this paper.

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