MINING GEOLOGY, 33(1), 1•`7, 1983

Minor Elements in Pyrite and Chalcopyrite from the Mamut Mine,

Takashi NISHIYAMA*

Abstract: Microanalyses were performed on principal minerals•\pyrite and chalcopyrite•\from the porphyry

deposits of the Mamut Mine, . The result reveals that Ag and Mn are concentrated in chal-

copyrite; and Mo, Ni, Co, Pb and Bi in pyrite. In general, the minor element variability in chalcopyrite is smaller

than that in pyrite. Minor element abundances in pyrite and chalcopyrite vary with host rock types. The Ni compo-

sition of the sulfide minerals is likely due to mixing of Ni from the host rocks with Ni derived from the ore fluid.

Comparing the analytical data from the Mamut deposit with those from the Bingham deposit and the Santa

Rita deposit, it can be pointed out that chalcopyrites in the former deposit are generally richer in Ag and poorer in

Sn, Mo, Bi and As than in the latter deposits.

began in 1975. Ore reserves are estimated at Introduction 178 million tons of 0.476 percent copper and The Mamut mine, located in the north- about 0.5 parts per million of . 28 pyrites western Saba, 68 kilometers east of Kota and 10 chalcopyrites from the of the Kinabalu, is a typical Mamut mine were carefully concentrated and in the southwestern Pacific islands (Fig. 1). The ore deposit was first discovered in 1964 by geochemical exploration and mining operation

Fig. 1 Index map showing location of the Mamut mine.

Received on November 11, 1982, accepted on December 15, 1982 * Department of Mineral Science and Technology, Faculty of Engineering, Kyoto University, Sakyoku, Kyo to 606 Keywords: Minor element, Mamut mine, Porphyry Fig. 2 Geologic map of the Mamut mine, showing of copper, Pyrite, Chalcopyrite. locations of samples.

1 2 T. NISHIYAMA MINING GEOLOGY:

Table 1 Description of samples.

qz: quartz fl: feldspar , am: amphibole , se: sericite , tal: talc , chl: chlorite

bi: biotite , mu: muscovite , ka: kaolinite , py: pyrite , cp: chalcopyrite then were analyzed by atomic absorption in the host rocks. Alteration, which is charac- spectroscopy to investigate the distribution of teristic of strong silicification and development minor elements among these minerals. of biotite, occurs in the ore-shell. The economic mineral is chalcopyrite and other sulfide mine- Samples rals found in significant amounts are pyrite and Geology and mineral deposits of the Mamut pyrrhotite. Minor concentrations of sphalerite, mine area have been discussed by many galena and molybdenite are present. Gold is authors (e.g., KOSAKAand WAKITA, 1978; found in sulfides and in the native metal. WAKITA,1981; NAKAMURAet al., 1970). The In the vicinity of the Mamut mine, several deposit is related to an upper Miocene adamel- small copper deposits are known to be present lite intrusion which has invaded sedimentary in the southeastern flanks of Mt. Kinabalu . At rocks and serpentinites (Fig. 2). Copper miner- Bambamgan, one of them, the deposit is alization is localized in the intrusion as well as composed of massive ore and disseminated ore. 33(1), 1983 Minor Elements in Pyrite and Chalcopyrite from the Mamut Mine 3

Table 2 Minor element content of pyrite.

28 hand specimens of sulfide ore were col- opaque mineral impurities is estimated to be 1 lected from various representative parts of the percent. deposits and host rocks in the Mamut deposit area and the Bambamgan deposit area (Fig. 2, Microanalysis and Measurement of Table 1). 10 samples were obtained from ser- Unit-cell Edges pentinite zone, 8 samples from sedimentary Each separated specimen was treated with rocks and hornfels, and 8 samples from adamel- aqua regia. The dissolved specimen was then lite. 2 samples of massive ore were prepared evaporatedto drynessand taken up with 1N from the Bambamgan deposit. HC1. The solution was diluted to a concentra- Pyrite and chalcopyrite were carefully sepa- tion of 0.02 g specimen/ml with 1N HC1. rated using techniques applicable for the Atomic absorption analyses were performed on physical properties of the minerals. Mineral these solution for Ag, Mn, Mo, Zn, Cd, Ni, separation techniques included isodynamic Co, Pb, Bi, In, Cr, Sn, Sb and As, employing a separator, elutriating tube, heavy liquids, Jarrel-Ash AA•\8500 atomic absorption spectro- selective leaching and hand picking of mineral graph. Analytical results are described in grains. The separated specimens were checked Table 2 and 3. for their impurities by X-ray diffraction Measurement of unit-cell edges of pyrites method. Judging from the sensitivity of X-ray was made by a Norelco X-ray diffractometer diffraction analysis, the maximum amount of with Fe filtered CoKƒ¿ radiation. Powdered 4 T. NISHIYAMA MINING GEOLOGY:

Table 3 Minor element content of chalcopyrite.

: pyrite from sll•¬s•¬one , •• : pyrite from hornfels, •¡ : pyrite from adamellite porphyry, •¬ : pyrite from serpen•¬inl•¬e , •~ : pyrite from massive ore. •› , ••, • ,ƒ¢ ,•¬ : average Fig. 3 Minor element distribution in pyrite.

Brazilian quartz was used as the external remarkable that the amounts of these elements standard for the measurements. The results are very variable, ranging from trace to 3,000 obtained from (440) spacing are shown in ppm. Some pyrites show relatively high con- Table 2. centrations of Mo (90-550 ppm) and Cr

Minor Element Contents in Pyrite and (310 ppm), though in most cases the values less than 50 ppm are observed. Ag is present in the Chalcopyrite range of 5-130 ppm; Mn<5-28 ppm; As<10- Pyrite: Pyrite is the most abundant sulfide 50 ppm. Cd, In, Sn and Sb were below the mineral in the primary ore, and is widely limits of detection in most of samples. It seems disseminated as small euhedral granular variety that the unit-cell edge of the mineral has no in the ore-shell and the country rocks. correlation with minor-element data (Table 2). Minor element analyses of pyrites are given Chalcopyrite: Chalcopyrite is widespread in in Table 2. Ni, Co, Pb, Bi and Zn are present in the ore-shell. The grain size ranges from very significant quantities in the mineral and it is fine to medium as much as 0.05-1 mm across.

•¬ 33(1), 1983 Minor Elements in Pyrite and Chalcopyrite from the Mamut Mine 5

Fig. 4 Minor element distribution in chalcopyrite. See Fig. 3 for abbreviations

Most of the chalcopyrite are associated with pyrite, pyrrhotite, and/or sphalerite. As shown in Table 3, chalcopyrite is lower in abundance of minor elements (except Ag and Mn) than pyrite. Six elements (Bi, In, Cr, Sn, Sb, As) are at or below the detection limits in most of chalcopyrite separates. Ag, Mn, Co and Ni are all present in small quantities. Zn and Pb are abundant. Taking into account the purity of the separates, the high concentration of Zn in four analyzed chalcopyrites suggests that sphalerite inclusions are present, and. it appears probable that Cd in sphalerite and Pb

•¬ : •¬ yr•¬e from silfsfone, •¬ : pyrile from hornfels, •¬ : pyrile from •¬mellife porphy•¬y, •¬ in galena contaminated as minute impurities : pyrite from serpenlini•¬e. •¬ : pyri•¬e •¬om mossive ore are the partial cause for the observed high con- Fig. 5 Variations of Ni and Co contents in pyrite centrations of the elements. In general, the illustrating defferences among siltstone, hornfels, minor element variability in chalcopyrite is adamellite porphyry, serpentinite and massive ore. rather smaller than that in pyrite. from hornfels and serpentinite show relatively Distribution of Minor Elements among high contents of Ni. Other minor elements such Different Wallrock Types and between as Ag, Mn and Co are comparatively uniform Different Mineral Species in concentrations. Minor element levels of KOSAKAand WAKITA (1975) found that pyrite from adamellite are low as compared copper mineralization is uniformaly distributed with those of pyrite from other wallrock types. through the deposit. However, the contents of Fig. 5 demonstrates the correlation between minor elements in pyrite. and chalcopyrite vary Ni and Co content of pyrite from various kinds greatly with wallrock types (Fig. 3 and 4). As of host rocks. On the basis of the wallrock types, shown in Fig. 3, Ni is abundant in pyrite from pyrite can be divided into some groups. SHOJIet hornfels and serpentinite; Mo in pyrite from al. (1977) have also described the similar re- hornfels; Pb and Bi in pyrite from siltstone; Cr lationship for the ore minerals. Considering in pyrite from serpentinite; Zn in pyrite from high content of Ni in the host serpentinites, it massive ore. In Fig. 4 analyses of chalcopyrite is suggested that the enclosing rocks were one of 6 T. NISHIYAMA MINING GEOLOGY:

Fig. 6 Distribution of minor elements in chalcopyrite taken from the Mamut mine, the Bingham mine and the Santa Rita mine.

the important sources of Ni in the sulfide copyrite, Ag and Mn are seen to be enriched in minerals. chalcopyrite; Ni, Co, Bi and As in pyrite. Mo, With respect to the difference in minor ele- which is one of the characteristic elements of ment distributions between pyrite and chal- the porphyry copper deposits, appears to be 33(1), 1983 Minor Elements in Pyrite and Chalcopyrite from the Mamut Mine 7

concentrated in pyrite and its content is very values than chalcopyrite from the Mamut de- variable, ranging from less than 3 ppm to posit. It appears that As is comparatively 550 ppm. enriched in chalcopyrite from the Bingham deposit. Comparison with Other Porphyry Acknowledgment: I wish to express my Deposits sincere gratitude to Professor Emeritus Taneo ROSE(1967) has given detailed descriptions of MINATO and Associate Professor Yoshihiko trace elements in chalcopyrite and sphalerite KUSAKABE of the Kyoto University, who have from the Central district and the Bingham given me much advice and criticism on this district, USA, including the typical porphyry work. I am indebted to the Oversea Mineral copper deposits such as the Bingham deposit Resources Development Company for my field and the Santa Rita deposit. In Fig. 6 are survey. Thanks are also due to Mrs. Hisae compared the minor element concentrations in YAMAZAKI for providing samples for chemical chalcopyrite collected from the Mamut mine, analyses.

the Bingham mine and the Santa Rita mine. References Significant change in distribution of minor ele- KOSAKA, H. and WAKITA, K. (1978): Some geologic ments among three deposits is observed. Con- features of the Mamut porphyry copper deposit,

centrations of Ag are found to be relatively high , Malaysia. Econ. Geol., 73, 618•`627.

and show small variation in chalcopyrites from SHOJI, T., IMAI, H. and TAKENOUCHI, S. (1977): Ion

the Mamut deposit, while chalcopyrites from microanalysis of the ore minerals from the Mamut the Bingham deposit and the Santa Rita deposit mine, Sabah, Malaysia. Mining Geol., 27, 323 are rich in Sri. Bi and Mo appear to be more •` 330. abundant and the amount of these elements is RosE, A. W. (1967) : Trace elements in sulfide minerals variable in the Bingham deposit. The distribu- from the Central district, New Mexico and the tions of Ni and Co in the Mamut mine are gingham district, Utah. Geochim. Cosmochim. rather similar to those observed in the Bingham Acta, 31, 547•`585. mine and the Santa Rita mine and the ranges of NAKAMURA, T., MIYAKE, T., KANAO, N. and TOMIZAWA, N. (1970): Exploration and prospect-

the contents are large, being from the detection ing in Mamut mine, Sabah, Malaysia. Mining

limits to less than 1000 ppm. Mn averages in Geol., 20, 106•`113.

these three deposits are almost the same, though WAKITA, K. (1981): The alteration and mineralization

chalcopyrite from the Bingham deposit and the of serpentinite of the Mamut porphyry copper Santa Rita deposit has a wider range of Mn deposit. Mining Geol., 31, 351•`365.

東 マ レー シ ア,マ ム ー ト鉱 山 産 黄 鉄 鉱,黄 銅 鉱 中 の

微 量 成 分 につ い て 西 山 孝

要 旨:マ ム ー ト鉱 山 は東 マ レー シ ア,サ バ 州 に あ る斑 岩 の種 類 に よ って異 な る 元 素 が 存 在 し,そ の 原 因 と し 岩 銅 鉱床 で あ る.同 鉱 床 の 主 要 鉱 石 鉱 物 で あ る黄 鉄 鉱, て,Niの 場 合 は鉱 液 と母 岩 との 反 応 が考 え られ る. 黄 銅 鉱 を分 離 し,そ れ らに含 まれ る14種 の微 量 元 素 を分 次 に,代 表 的 な斑 岩 銅 鉱 床 で あ る ビ ン ガ ム鉱 床,お よ 析 した.そ の 結 果,次 の よ うな こ とが 明 らか に な っ た. び サ ン タ ・リタ鉱 床 産 の 黄 銅 鉱 中 の微 量 成 分 とマ ムー ト (1) Ag, Mnは 黄 銅 鉱 に多 く 含 ま れ, Mo, Ni, Co, Pb, 鉱 床 産 の もの とを比 較 検 討 した とこ ろ,マ ム ー ト鉱 床 に Biは 黄 鉄 鉱 に多 く含 ま れ て い る.(2)微 量 成 分 の 含 有 量 はAgが,ビ ン ガ ム鉱 床 あ る い は サ ン タ ・リタ鉱 床 には の変 化 は,黄 鉄 鉱 に比 べ る と黄銅 鉱 の 方 が 一 般 に 小 さ Sn, Mo, Bi, Asが 多 く含 ま れ て い る こ とが判 明 した. い.(3)硫 化鉱 物 中 の微 量 元 素 の含 有 量 は 含 ま れ てい た 母