Microanalysis has been conducted to find out the distribution of minor elements in pyrite and chalcopyrite in the ores and host rocks from the Shakanai Mine which is one of the typical poly-metal ore deposits called in Japan by the name of Black Ore Deposits. It is composed of dense aggregates mostly of sulfide minerals. To separate pyrite and chalcopyrite from ores and host rocks is very difficult and laborious, but by using heavy liquids, isodynamic separators, elutriating tubes and so on repeatedly, pyrite and chalcopyrite can be purified to a very high degree.
In this study, first, 23 samples of pyrite and 17 samples of chalcopyrite were separated trom ores and host rocks. Next, the qualitative analyses of these samples were made by Jarrel-Ash Evert-type 3.4m grating spectrograph (JACO). As a result 22 elements from pyrite, and 18 elements from chalcopyrite have been detected. These data were studied in reference to the localities of the samples, and the following conclusions have been drawn.
(1) Most of minor elements in pyrite and chalcopyrite show clear differences between ores and host rocks, that is, Ag, As, Ba, Bi, Cd, Cu, Ge, In, Mn, Sb, So, and Zn content in pyrite and As, Ba, Bi, Cd, Cr, Ga, Ge, Mn, Pb, Sb, Sn, and Ti content in chalcopyrite indicate higher values in ores and lower values in host rocks. On the contrary, Co, Ni, and Ti content in pyrite are concentrated in host rocks.
(2) As a result of field survey, the selected ore body is divided into seven more little unit-ore-bodies. The samples of pyrite and chalcopyrite from each unit-ore-body include various different quantities with respect to a few minor elements like Ba, Bi, In, and Sn. The other elements were not recognized a distinct difference between them.
(3) According to the findings of Kajiwara (1970), some veins are considered as feeder channels through which the ore-forming solution was supplied. So pyrite and chalcopyrite-rich part, sphalerite and galena-rich part and clay-rich part were selected from a typical vein located under the ore body. The contents of minor elements in those three parts were then compared with those in the ore body. The comparison shows that the behavior of most minor element contents except Bi, resembles that in ore body. This fact probably suggests that the vein has been a feeder channel, and this presumption agrees with the data obtained by field investigations.
(4) The distributions of minor elements in pyrite and chalcopyrite are classified into two groups-the regular group and the irregular group. The regular group to which many elements belong, shows such distinct tendencies as in almost all of pyrite-chalcopyrite pairs, and As, B, Ba, Cd, Co, Mn and Ni element are always enriched in pyrite and Ca, Cr, Ga, Ge, In, Sb and Zn element are enriched in chalcopyrite. This fact may be explained by the differences in the temperatures or other conditions of the ore-formation. The other group including six elements such as Ag, Al, Bi, Mg, Pb and Sn shows irregular variations in the amount of above-mentioned elements, for in some cases they are concentrated in pyrite and in other cases they are found concentrated in chalcopyrite.
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