There are several igneous rocks in the Kamaishi mining district. Ganidake igneous complex, which is mainly composed of Ganidake granodiorite, diorite-diorite porphyry and monzonite, plays an important role on skarnization and mineralization. The complex was studied in detail and compared with Kurihashi granodiorite and so-called Sennin porphyrite, which are unrelated to mineralization. The results of this study are summarized as follows.
1) Ganidake granodiorite body swells downward, especially at the northern part, while Kurihashi granodiorite body pinches out in the depth.
2) On the fissure pattern study, two different directions are observed. The N-S trend fissures which were formed at the same stage as mineralzation are predominant in the northern part of the granodiorite, and the post ore E-W trend fissures are predominant in the southern part.
3) Ganidake igneous complex has been suffered from remarkable hydrothermal alteration along the fissure zone of N-S trend, and Ganidake granodiorite gives relative addition of Na₂O and K₂O to the surrouding diorite and so-called Sennin porphyrite.
4) It is revealed that magnetic susceptibility depends on the magnetite content and that it becomes low near the alteration zone and ore deposits.
5) Chlorine and copper contents of Ganidake granodiorite which are considered to have genetical relation to the skarnization and mineralization, are higher than those of the Kurihashi granodiorite.

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The Toyoha mine, Sapporo city, is well known for its fissure filling type silver-lead-zinc ore deposit. The vein swarm of the mine appears in complicated volcanic and pyroclastic pile believed to be formed during so-called "Green Tuff Orogeny" of Neogene Tertiary period. The pile is composed of basaltic propylite, rhyolite, conglomerate, sandstone, mudstone, green tuff and andesitic propylite in ascending order. Several decades of ore vein including three major ones have been known in the mining district. The Tajima vein, running from east to west at northern part of the area, the Soya vein, crossing the preceding one with NW-SE trend and the Izumo vein, running parallel with the Tajima vein at southern part of the area are the most evaluated ore veins in this mine. The others are regarded to be subsidiary and/or satellitic. The present authors interprete some characteristics of the newly found Izumo vein in this paper. The Izumo vein, 600m long with the width of 2-6m, has recently become to be expected that this vein extends more than 300m along the dip by the underground prospecting and the diamond dillings. The Izumo vein is distinguishable from the other major veins based on the poorness of quartz and galena, richness of sphalerite and pyrite. Furthermore, it is noteworthy that tin minerals have been recently found from the Izumo vein. The new discovery of the tin minerals is much indebted to Mr. J. YAJIMA, Geological Survey of Japan, who detected them stannite and cassiterite.

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Matsuki deposit is located in the southwestern part of Odate basin and is known as one of the Kuroko deposits occurring in the acidic pyroclastic rocks and mudstone of Miocene age. Sulphide orebody is mainly composed of yellow ore, pyrite ore and small amount of black ore. There are following three mineralized horizons; the lower part of M₂ member (called as "A" ore deposit), the boundary part of M₂ and T₃ member ("B" ore deposit) and the upper part of T₃ member ("C" ore deposit). "A" ore deposit is composed of several unit ore-bodies which are pan-shaped high-grade yellow ore. "A" ore deposit is divided into the coarse porous orebody and the fine banded one on the basis of modes of occurrence and mineral assemblage. The country rocks of "A" ore deposit are strongly argillized. Clay minerals occurring in this argillized zone are abundant interstratified Mgchlorite/saponite and minor interstratified sericite/montmorillonite and montmorillonite. In "A" ore deposit, a lateral zonal distribution of minerals, sulphide ore zone, gangue minerals zone, black clay zone from center to periphery of the mineralized zone is recognized. Sulphide ore zone is divided into yellow ore sub-zone and black ore sub-zone from center to outside and gangue minerals zone is also divided into barite lens sub-zone and siliceous lens sub-zone from center to outside. Carbonate lenses are sometimes found in the boundary of barite lens subzone and siliceous lens sub-zone. "A" ore deposit is thought to be formed in the unconsolidated M₂ mudstone after deposition of the lower part of M₂ mudstone. The exploration was conducted on the basis of above-mentioned geological and mineralogical investigation and consequently some high-grade orebodies have been found in the lower part of M₂ mudstone.

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The Matsumine is the largest Kuroko deposit in Japan, situated in western margin of the Hokuroku district, Akita Prefecture. In October 1966, the first production was started at the rate of 20, 000 tons of crude ore per month and the rate was increased in the following years up to 50, 000 tons per month. Total production of crude ore since the beginning of operation amounts to more than 5 million tons. The stratabound ore deposits in the Matsumine lie 200m to 400m below the surface, and extend horizontally in the area N-S 800m and E-W 600m.They are all distributed in definite stratigraphical horizons of Hanaoka formation of the Miocene Tertiary and divided into three units, which are called lower, middle, and upper ore beds. In each of these units, the zoning according to the mineral assemblage are observed such as pyrite ore, yellow ore, and black ore in ascending order. Generally the lower ore is rich in yellow ore and poor in black ore, the middle one consists of black ore and yellow ore, and upper one is dominant in black ore. A recent prospecting in this mine has performed from the center of mineralized area to the outward and the downward. A new method of upward drilling has investigated the black ore of the upper ore bed. As the results of these works, the following objects have been made clear.
1) Mode of occurrence on three ore beds (upper, middle, and lower), and the mineral composition of ore in each bed.
2) Existence of four lava domes of rhyolite and the form of each dome, which are closely related to the genesis of the ore deposits.
3) Mineralization in the footwall under the stratabound deposits.
4) Internal structures in the ore deposits.

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The Huanzala Mine is a copper, lead and zinc mine in Peruvian Andes. Being emplaced in a limestone formation of Cretaceous Period, its ore bodies occur bedded and lenticular in form along approximately definite horizons. Two types of mineralized zones are recognized. One called the inner pyrite zone occurs in the ore horizons such as the mantos from 1 to 5 and is closely associated with Cu, Pb and Zn ores, while the other, the outer pyrite zone, occupies the area between the ore horizons of the former type. The latter type consists of large, massive and replacement ore bodies with scarce association of Cu, Pb and Zn ores.
Distribution of Cu, Pb, and Zn ores is limited to the areas 200 meters from the inner pyrite zone. Zonal distribution of ores is recognized megascopically in the order of pyrite-Cu, Cu-Zn, Zn-Pb and limestone, from the center outwards. The zonal distribution is likewise recognized by using metal ratio, π, Zn=(Assay Zn)/[Assay(Cu+Pb+Zn)×100. Within a mineralized horizon, a few inner pyrite zones are scattered and the matrix is occupied by Cu, Pb and Zn ores. The principle of exploration in the Huanzala Mine is to investigate distributions and shapes of the inner pyrite zones. Metal ratios are helpful to indicate the possible locations of unknown ore zones.

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The Gran Bretaña Mine is located about 140 kilometers to the east of Lima, Central Peru, and has been developed since 1960 as a high grade zinc mine in the central Andes poly-metalliferous zone. The rock units in the mining field consist of sedimentary formations ranging from Early Jurassic to Early Tertiary in age and intrusive rocks of Miocene or Pliocene age. Azulcocha deposit, a major one of the ore deposits of the Gran Bretaña Mine, consists of two orebodies. The one is zinc orebody consisting of mainly sphalerite with minor pyrite, barite and arsenic minerals, and the another one is manganese orebody. The deposit is situated along the Gran Bretaña reverse fault with E-W trend, and is interpreted to be formed as low temperature replacement deposit in limestone bed of Pucara Group of Jurassic age. Geological factors controlling ore deposits are concluded to be as follows:
1) Azulcocha deposit is situated in the outer zone of the mineral zonation which surrounds Chuquipite granodiorite intrusive. Relationship between mineralization and intrusives of Miocene or Pliocene age is observed in the mining field.
2) A large number of known orebodies in the mining field are located in the favorable limestone beds of Pucará Group and Middle Cercapuquio Formation of Jurassic age.
Stream sediment geochemical survey and I.P. geophysical survey were carried out in the mine area. As a result, it is concluded that both methods are useful.

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The Kutcho Creek area is located 105 kilometers southeast of Dease Lake in northern British Columbia, Canada. Exploration works on the property commenced in 1972, and were followed by geological, geochemical and geophysical investigations in 1973. I.P. anomalies associated with low resistivity were drilled successfully and a Kieslager type stratabound massive sulphides deposit was discovered in 1974. Charged potential surveying including drill hole measurement has been effectively applied to Kutcho area since the deposit was discovered, and has provided very useful information on the mineralized zones.

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