The Huanzala mine is a poly-metallic mineral deposit associated with copper-silver-lead-zinc in the Peruvian Andes. The ores have replaced certain horizons of limestone beds of the Lower Cretaceous, and the ore bodies are platy or lenticular in form and concordant with the host-rock stratigraphy. During the recent deep DDH exploration program, which was planned and implemented based on a reanalysis of existing geological information, a prominent mineralized zone with large potential was discovered 200m below the current operating zone. This new mineralized zone occurs in limestone blocks which are the downward continuation of the current operating zone. These blocks were thrust downward by the reverse fault (the so-called “Lower Fault”) and then subjected to hydrothermal metasomatism. Mineralization is in the form of copper-silver and copper-zinc minerals occurring with skarn and massive pyrite. The Huanzala mine consists of two independent districts: the north deposits, and the south deposit. In addition, the mineralization is interpreted to have occurred in two stages: in the first stage, the pyritic ore and the skarn ore formed mainly with silver-lead-zinc mineralization accompanying the granodiorite porphyry, and in the second stage, so-called “Shiroji” ore containing copper-silver-lead-zinc mineralization accompanying quartz porphyry was deposited. From 1964 until recently, systematic exploration and development of the Huanzala mine had focused on the strike-extension zones horizontally to the north and to the south of the known deposits. However, the strike extension exploration program was recently completed and the remaining potential zones in the operating area are running out. As production is depleting the ore reserves, the discovery of a new exploration target area has significantly contributed additional ore reserves for the Huanzala mine.

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1:200,000 scale quadrangle geological maps of the Attapeu area in southern Laos were created by Japan International Cooperation Agency (JICA) as a part of the Development Aid Project "Geological Mapping and Mineral Information Service Project". These geological maps consist of "Attapu" district and "B.Dakyoy" district. The area of the created maps lies between 14°40' N and 15°20' N in latitude and 106°00' E and 108°00' E in longitude. The geology of the Attapeu area consists of varieties of rocks such as gneiss, gabbro, granite, schist, slate, sandstone, conglomerate, marine to continental sedimentary rocks of chert and limestone, rhyolitic and basaltic volcanic rocks. The metamorphic rocks in the area are thought to be related to a collision of continental crust. Distribution of these rocks is settled respectively and forms structural terrain. The age of each layer of geological unit tends to become young toward the west. The following period is assigned for each geological unit based on the available data. The gneiss and gabbro unit is Precambrian or unknown, granite units are Ordovician to Triassic, and the metamorphic rock unit is supposed to be Ordovician to Carboniferous. For the post orogenic volcanic and sedimentary rocks, the age of rhyolitic to andesitic volcanic rocks and chert and limestone are Triassic, the marine sedimentary rocks are Carboniferous to Jurassic and the continental sedimentary rocks are assigned to Jurassic to Cretaceous, respectively. For the basaltic volcanic rocks, Cretaceous and Tertiary periods are assigned. Mineral resources which occur in the Attapeu area are gold, copper, bauxite, rare-earth, gems, bentonite, kaolin, aggregate and coal. Gold and copper prospects occur in the western side of Annam mountain, Kontum massif. Gold and copper prospects may be orogenic type and porphyry copper type related to Paleozoic to Mesozoic tectonics, respectively. A copper prospect in the north of the area is sediment-hosted copper type. Bauxite deposits and rare-earth enriched laterite are related to weathering, and placer gemstones to basaltic plugs of Tertiary to Quaternary age.

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The Atalaya prospect area is located at latitude 10°01'S, longitude 76°57'W in Ancash Department, Republic of Peru. Compania Minera Santa Luisa S.A., a subsidiary of Mitsui Mining & Smelting Co., Ltd., and Mitsui & Co., Ltd., have been exploring the area occasionally since 1979. The area consists of gently folded Cretaceous sediments and Tertiary intrusive. The zinc mineralization is recognized in the skarn formed in the limestone around the granite porphyry intrusive. Major zinc mineralization is shown in the skarn of the Pariahuanca Formation and the Jumasha Formation around Azulcocha, Minas Punta and Santa Clara. In the present exploration campaign which commenced in 2006, Santa Luisa has undertaken surface mapping, geophysical study and drilling. The drilling program, which began in August, 2007 had finished 34 diamond drillings totaling 9,586m by the end of 2008. As a result, 28 holes intersect more than 5% of zinc, and 9 holes over 50m intersects with zinc mineralization. Broad low-grade zinc mineralization is known to occur over almost entire area. The mineralization is not blocked yet and the still open to north and south extension. The further exploration work is necessary to define characterize the mineralization of the area.

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The Athabasca Basin in northern Saskatchewan is a well known uranium producing area. Three mines Rabbit Lake, McClean Lake, and McArthur River-Key Lake in 2008 produced 23.4 million lbs U₃O₈, about 20% of total world production. The uranium mineralization in this area is called unconformity-type, and typically occurs near the unconformity between basal Aphebian meta-sediments and the overlying Helikian age fluvial sandstones. The high grade deposits occur from near surface to about 800 m depth and are difficult to find because of the extensive sandstone cover. Airborne and ground geophysical surveys followed by drilling are the principal exploration methods. Environmental regulatory process for mine development also takes a long time, due to strict regulations; a lead time of 10 to 15 years from discovery to production is common. A Japanese uranium mining company, OURD, joined the Midwest and McClean Lake projects in 1991 and 1993 respectively. The McClean Lake project started production in 1999 and by the end of 2008 has produced 44.7 million lbs U₃O₈ from the JEB, Sue A, Sue C, Sue E, and Sue B deposits as open pit mines. McClean and Caribou deposits still remain to be mined, pending favorable economic conditions. For the Midwest deposit, found in 1978, various types of mining methods and environment impact studies have been undertaken and a production decision to develop it as an open pit mine was taken in late 2007. However, because of a significant increase in capital costs coupled with the current world economic crisis, a decision to postpone the development was taken in late 2008. The Midwest project is now on hold until the economy and uranium markets improve. Exploration drilling at the Midwest project re-started in 2005 after a long period of inactivity. Follow-up drilling near a mineralized hole drilled in 1980 resulted in discovery of the Midwest A deposit, some 3 km northeast of the Midwest deposit. The Midwest A deposit contains resources of about 10 million lbs U₃O₈.

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The ATACAMA KOZAN mine is an underground copper mine which is located in the suburbs of Copiapó City,the III Region of the Republic of Chile. It commenced exploration activities in 1991, and production of high quality copper concentrate from 2003. Cu-grade and tonnage data, which should be estimated in each stage of mine development (exploration, F/S, development and operation), are most important factor for decision of mine development and for steady operation of mine. Here we report grade-tonnage estimation methods in the ATACAMA KOZAN mine, and the history and excellent result of improvement on the estimation method. Geological model of copper deposit in the ATACAMA KOZAN mine was modified from "Breccia type" at initial stage of exploration to "Manto type" at main stage of exploration, and finally it is considered to be "Manto-Breccia composite type" in proportion to accumulation of exploration data in the each stages of initial exploration to later exploration in production. Following to the modification of the deposit model, grade-tonnage estimation method was improved repeatedly from square inverse distance method in the period before the development of the mine to Kriging method using variogram model in the period after commencement of production. Furthermore, improvement of the estimation method was kept on even after adoption of Kriging method. While in the period of "Stage 1" Kriging method using variogram model was adopted, in the period of "Stage 2" we adapted "Variable variogram model" for grade-tonnage estimation, which can transform direction of variogram model to fit elongation of ore body. In order to eliminate such a bad influence that grade of "Manto type"body is evaluated excessively near high grade"Breccia type" body, we have invented newly "Composite method" in the period of "Stage 3", with which grade in each "Manto type" and "Breccia type" bodies are calculated independently at first, then the all calculated grade is composited together. Grade-tonnage model estimated with "Composite method" showed very good coincidence with the final grade-tonnage data just before exploitation. As a result of these efforts, a grade-tonnage estimation method was established, and this trustworthy method is contributing considerably to steady operation of the ATACAMA KOZAN mine.

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In order to know In-concentration in skarn-type deposits, which have not been well studied relative to vein and massive sulfide types, sphalerite-rich tin skarn ores from the Hoei mine were analyzed. The In-contents vary from 1 to 496 ppm. In assuming that the indium is all substituted in sphalerite, In_sp is calculated, which varies from 851 to 2198 and averaged as 1715 (n=7). This value is the same order of magnitude as that of zinc concentrates of the famed Toyoha mine (In_sp=1431). Although indium concentration has been observed from high temperature exit of the ore fluid in the Toyoha Pb-Zn deposits to an epithermal gold environment at Nishizawa, economically important concentration can be expected in a hightemperature hydrothermal stage, including even skarn-type mineralization.

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Mineral resource papers presented at the 50th anniversary symposium of the Geology Department of the Chulalongkorn University held in Bangkok are briefly reviewed. The most distinct feature is lack of tin studies, although Indonesia still keeps the second position in the world tin production. Deeply weathered-type deposits such as Monywa (Cu-sulfides in Myanmar) and Padang (Zn-oxides in Thailand) are interesting reflecting their climate. Weathering processes including HREE in weathered granitic crust may be important subject to study in the coming years. Chatree gold deposits are the first large non-vein and skarn type discovered in Mesozoic volcano-granitic terranes in East Asia including eastern China coast and Japanese Islands.

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