The Hishikari gold mine consists of three epithermal vein-type Au-Ag deposits, named Honko, Yamada, and Sanjin. Honko deposit, which was discovered in 1981, has been producing gold and silver at the rate of 350-400t per day since 1985. Yamada deposit, located at 1.2km southwest of Honko deposit, was discovered in 1988 by surface drilling and started production in April 1991. Chemical analyses of 37 elements were carried out on 282 ore samples from Honko deposit and 142 samples from Yamada deposit. The samples are collected from drill core drilled from both surface and underground. As a result of the statistic analysis (correlation and principal component analysis) for the chemical compositional data, there are some differences between ore of Honko and of Yamada. For instance, they are,
(1) The ore of Honko is richer in most of the elements than that of Yamada, but is poorer in As, LOI, Mn, and Ni.
(2) The standard deviation of K ₂0 is larger in Yamada.
(3) Sb is concentrated in the high Au grade ore zone in Honko, while Sb and Au are hardly correlated in Yamada.
(4) The factor loadings of Factor 2 may indicate that Au-Ag mineralization, and range of high scores of Factor 2 was between 100ML and 40ML in Honko, but was not identified in Yamada.
These differences may suggest that the chemical condition or environment of formations of Honko and Yamada deposit was not similar.

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El Roble Mine is located in Carmen de Atrato, Departamento del Choco, Colombia. The ore deposits are classed as submarine volcanogenic massive sulfide type.
The purpose of this paper is to describe geological features so far acquired during exploration. The features are summarized as follows:
(1) This area consists of basic volcanic rocks, sedimentary rocks of Cretaceous age and intrusive rocks of Miocene age. The basic volcanic and sedimentary rocks are distributed under the structural control of NW-SE and N-S fault systems. The ore deposits are located along the contacts between the basic volcanic rocks and sedimentary rocks.
(2) The basic volcanic rocks belong to tholeiite series, but their properties, especially the contents of trace elements and clinopyroxene compositions from the area around the deposits are different from the other areas. It seems that the basic volcanic rocks around the deposits are less differentiated than that of the other areas in magmatic differentiation. Supposing that is the case and ubiquitous, these analytical method can be applied as the useful clues to target the possible areas.
(3) Silicification and carbonitization are observed in the sedimentary rocks along the contacts between the basic volcanic and sedimentary rocks. Such alteration is notable particularly in black shale around the deposits. Also the forms of the ore bodies are concordant with the black shale. These facts suggest that the deposits have a genetical relation to the interaction between the presence of black shale or its tectonic environment and the tholeiitic igneous activity.
(4) The dykes are divided into two types: one is fresh andesite or lamprophyre, and the other is intensely altered andesite. But the K-Ar dating of these dykes results in the similar ages between 13 to 16 Ma, i.e. Miocene in age. The whole rock analysis indicates that these dykes have calc-alkalic or shoshonitic compositions.
(5) Main ore minerals are composed of pyrite and chalcopyrite, and classified into Type A and Type B according to the occurrence of pyrite. Type A ore is characterized by colloform or framboidal texture, and common occurence of electum, tetrahedite as gold and silver minerals, whereas Type B is composed of commom euhedral to subhedral pyrite crystals and chalcopyrite-pyrrhotite matrices.
(6) The ore deposits are massive in form and considered to have syngenetically formed in the rocks of Cretaceous age. But the high contents of Cu, Au and Hg in the dykes of Miocene age indicate the remobilization and addition of metal elements.

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It has become common to use computers in resource development. Most common among those is to use a computer as a numerical calculation tool. The others are utilizations as a tool to assist engineers in judgement for technical questions. They are called an expert systems or some expert systems are reported in last 10 years and a number of systems are in actual use. We have attempted to develop an expert system to evaluate the favorability of the uranium exploration projects using the "Data directed Numerical method" (MCCAMMON et al., 1986). The system was implemented on the Macintosh personal computer and was designed so that the users can easily make the most of the iteration of trial and error process of the method.
In this paper, the application examples of the developed system are described for Alligator Rivers Uranium Field in Australia. The Alligator Rivers Uranium Field is one of the famous uranium provinces in the world. Five exploration parameters were selected by a statistical analysis of the relationship between the exploration parameters and the presence of the known uranium deposits and occurrences. The favorability evaluations were performed for four different cases of two types of uranium deposits, namely the Jabiluka-Type and the Nabarlek-Type.

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