From the mineral paragenetical standpoint, the copper ores of the world are classified into the following types :
(1) Chalcopyrite-pyrite ores.
(2) Cupriferous iron sulphide ores.
(3) Copper-zinc-lead-bearing iron sulphide ores.
(4) Nickel-bearing pyrrhotite ores.
(5) Disseminated copper ores (porphyry copper ores).
(6) Arsenic-bearing ores.
(7) Tin-tungsten-copper-lead-zinc-bearing polymetallic ores (xenothermal type).
(8) Cobalt-bearing ores.
(9) "Kupferschiefer" ores.
(11) Native copper ores.
(11) Supergene (secondary) copper ores.
Characteristic features of each ore type are briefly described. Mutual relationships of their occurrences are explained.

View full abstract

The Yatani mine is located in the southwestern part of the Yonezawa Basin, Yamagata Prefecture, which is known as the so-called "green tuff" area.
The geology of this area composed mainly of the Miocene pyroclastic and sedimentary rocks. The stratigraphy is in ascending order as follows : the Koarasawa formation, the Karasugawa formation the Yatani formation and the Otoge formation.
The ore deposits in the Yatani formation (acidic pyroclastic rocks and black mudstone) are of epithermal fissure-filling vein type. They may be classified into two types by their mineral constituents, Pb-Zn veins, and Au-Ag veins.
The Pb-Zn veins consist of galena, sphalerite, pyrite, small amounts of chalcopyrite, native gold, argentite and Mn-minerals. They have a general strike of E-W.
The Au-Ag veins consist of native gold, argentite, chalcopyrite, quartz, johannsenite, rhodochrosite, rhodonite, calcite, small amounts of pyrite, sphalerite, galena, adularia and chlorite. They have a general strike of NE.
The writer described mainly the occurrences of the Au-Ag veins.

View full abstract

By recent explorations, the new black ore deposits of ginzan under thick volcanic cover of the Quaternary age have been discovered in the northeastern area of the famous Kosaka mining district. The geological occurrences of the ore deposits are very similar to those of the Hanawa ore deposits which are located far southward.
The stratigraphic horizon of the new deposits is also in the upper part of the Nishikurosawa stage roughly corresponding to the Burdigalian, as in the most cases of black ore deposits in the region.
The structural position of the new deposits is near the margin of the Namariyama sub-basin in the west of the elongated Towada basin, in which southern part the Hanawa deposits occur. This subbasin is located close to the northeast of the large circular Hokuroku basin, where along the margin many important black ore deposits have been in operation. The discovery of the new deposits may be a promissing guide to further exploration in this sub-basin.

View full abstract

The Omidani Mine is located at about 4km southwest of the Akenobe Mine. The geology of the area consists mainly of Palaeozoic formations (Maizuru group), with several intrusives of the Cretaceous to earlier Tertiary age.
The ore deposits are composed of many gold-bearing silver quartz veins, all of which occur mostly in slate and sandstone alternations of the maizuru group.
The Fusei deposit, which has been extensively developed in the mine, has the vein pattern of an acute intersection by two directions of WNW and NW, dipping 60°to 80° north or south. There are many bonanzas along andesite dikes. Each unit vein has width of 40-150 cm, strike length of 30-200 m, and plunge length of 60-300m.
Principal ore minerals are argentite and native silver. The average grade of ores, which recently has been produced, is 1.5-2g/t Au and 450-480g/t Ag.
Geophysical prospecting (resistivity method) has been successful in locating the Au-Ag-quartz veins in slaty rock.

View full abstract

It has been proved that shapes of the mineralized zones depend on the location of intrusive granite porphyry, which appears to be the ore bringer, large fractures and fissures, and plunges of limestone bodies. In the mineralized zones, the zonal distribution of ores were clearly recognized. Namely, surrounding the molybdenite-bearing granite porphyry the zones of predominant ore metals are in the following order : Mo-Cu-Cu : Zn-Zn-Zn⋅Pb-Pb. Metal ratio, ρ_Pb=Pb%/Pb%+Zn%×100, is very useful index for the quantitative indication of the zonal distribution. It was shown that ρ_Pb values for the different zones become higher outwards as the distance from the granite porphyry increases. The geological structure shows a reverse S-letter pattern which was caused by the movement of Nanagohi drag fault, with folded limestone bodies plunging 45 to 50 degree to southwest.
Consideration on the shape of the mineralized zone, zonal distribution, and structure of limestone suggested the location of the mineralization, sort of ores and grade of ores at the deeper part of the Mozumi mining area. It was also inferred that workable ore deposits should be expected even under barren limestone zone merging with slightly mineralized zone downward in the southern part of the Mozumi area.
As the result of explorations based on the above-mentioned ideas, new ore reserves, 1, 518, 000 tons of lead-Zinc ore and 171, 000 tons of copper ore, totalling 1, 689, 000 tons, have been discovered since 1962 to 1968. In future exploration, discovery of more ore bodies can be expected in the southern district, where active prospecting works have been in progress on the -320 meter level, becouse of several indications of hidden ores and many other mineralization.

View full abstract

The Nakanosawa area, situated in the southern vicinity of the Shimokawa mine, is composed of the pre-Cretaceous black slates, various kinds of diabasic rocks, serpentinite and gabbro. General geological setting of the area is quite same as that of the producing area of the mine.
One of conspicuous features of the area is the broad shear zone sub-parallel to the western main diabasic mass that contains abundant intercalated slates. This shear zone, containing also lenticular bodies of diabasic rocks and gabbros, has a width of several hundred meters merging undisturbed slate zone to the east.
Three mineralized zones were detected within the shear zone. The main mineralized zone runs only on the hanging wall of the main diabasic mass, and corresponds to the horizon of champion ore bodies of the mine. The intermediate mineralized zone has only several ore stringers. The eastern mineralized zone is characterized by disseminations of granular pyrite, whose cracks are filled by pyrrhotite.
By recent exploration drillings of this area small cupriferous pyrite ore bodies are discovered in the deeper part of the main mineralized zone. This warrants further prospection in this area.
The occurrences of diabasic rocks and the intercalated slates are very complex. However, the coarse-grained nature, existence of spilitic facies with pillow structure, whitish coloration by abundant carbonate veinlets, and assemblage of the sulphide minerals may be usefull guide to distinguish the main diabasic mass and its hanging-wall main mineralized zone from the other diabasic rocks and mineralized zones.

View full abstract

Encouraged by the discovery of blind Fujimi deposits in the Hitachi main ore zone, the active exploration by underground tunnelings and core drillings has been carried out in the neighbouring area of the mine since 1960. Thus, geological and stratigraphic interpretation of the crystalline schist formations around the mine gave the promissing idea for the new discovery of blind ore bearing zone in the eastern part.
In 1965, new bedded cupriferous pyritic deposits, the Fudotaki deposits were discovered in the green schist zone of the Upper part of the Akasawa Formation, which are situated about 150m below the serface and 1, 500m to the southeast of the Hitachi main ore zone.
Since then, the prospecting works of 56 drillings totalling 8, 900m and tunnelings of 8, 170m have proved four ore bodies in the distance of 1, 300m on the same ore zone.
The largest ore body has so far the maximum strike length of 220m, maximum width of 15m and dip length of 175m. The tenor of ores is 2.20% Cu, and 40.10% S. Further prospecting works are in progress for the deeper levels of the deposits.

View full abstract

Le but principale de ce rapport est de donner une vue des gisements de Nickel de la Nouvelle-Calédonie.
On peut connaitre qu'il y a deux types figuratifs sur le gisement de la Nouvelle-Calédonie, dont l'un, type trouvé principalement à son côté ouest, s'etend parallèlement à la surface du sol comme coussion développé, et dont l'autre, type trouvé au côté est, représente une forme de filon présque vertical. La genèse de ce premier type de gisement peut être expliquée par des conditions topographiques et ce dernier par des lignes tectoniques faibles propre à une roche-mère.
Appelons ce premier "Gisement topographique" et ce dernier "Gisement tectonique".
Le gisement topographique est en général couvert de latérite épaisse. Par contre, la latérite du gisement tectonique n'est pas tellement épaisse.
On peut facilement trouver la roche-mère non altérée à côté du gisement filonnien. Au contraire, il est diffcile à la trouver à la region du gisement topographique.
II serait très intéressant de comparer ces caractéristiques des formes du gisement avec les compositions de minéraux.
Les composants principaux des minerais produits dans le gisement topographique sont ferrimontmori-llonites caracterisées par l'altération relativement homogène.
Dans le terrain minier dont le gisem ent est tectonique, on produit des minerais ayant de serpentine comee composant principal.

View full abstract

The tin mining in Malaysia has been mainly based on the exploitation of placer tin deposits in "the tin belt", through the Malay peninsula from north to south. Cassiterite in placer deposits are absolutely isolated and associated with such heavy mineral sands as ilmenite, zircon, monazite, xenotime, etc.
Prospecting for placer tin is carried out by means of empire drilling called Bangka drilling. Among many mining methods, large-scale dredging and small-scale gravel pumping are quite popular in Malaysia, while the latter produces the major portion of tin concentrates. In ore dressing, sluicing with palong for rough concentrates and cleaning with huddle called lanchute are still used in most of gravel pump mines.
The writers review the tin mining, local method of ore dressing, the outline of geology and some features of tin ore deposits in Malaysia on the basis of field survey conducted during past several years.

View full abstract