Majalah Geologi Indonesia, Vol. 27 No. 1 April 2012: 1-11
Characteristics and the Occurrence of “Garnierite” from the Soroako Nickeliferous Laterite Deposits, Sulawesi, Indonesia
Karakteristik dan Keterdapatan Garnierit pada Endapan Laterit Nikel Soroako, Sulawesi
Sufriadin1, Arifudin Idrus2, I Wayan Warmada2, Irzal Nur1, Shigeki Ueno3, and Akira Imai3,4
1Mining Engineering Study Program, Hasanuddin University, Jln. Perintis Kemerdekaan Km. 10 Tamalanrea, Makasar 90245, Indonesia 2Department of Geological Engineering, Gadjah Mada University, -OQ*UD¿ND%XODNVXPXUYogyakarta 55283 Indonesia 3Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan 4Department of Earth Science and Technology, Akita University, Akita 010-8512, Japan
ABSTRACT An investigation of Ni-Mg hydrous silicate ores called “garnierites” from the Soroako nickeliferous laterite deposits has been conducted by means of optical microscopy, X-ray diffractometry (XRD), and ;UD\ÀXRUHVFHQFH ;5) VSHFWURVFRS\ZLWKWKHDLPVDWGHFLSKHULQJWKHRFFXUUHQFHVPLQHUDORJ\DQG EXONFKHPLFDOFRPSRVLWLRQRIJDUQLHULWH6DPSOHVZHUHFROOHFWHGHLWKHUIURP:HVW%ORFNRU3HWHD%ORFN 7KH:HVW%ORFNLVPRVWO\RFFXSLHGE\XQVHUSHQWLQL]HGSHULGRWLWHZKHUHDVWKH(DVW%ORFNUHSUHVHQWHG E\3HWHDDUHDLVFRYHUHGE\PRGHUDWHO\WRKLJKO\VHUSHQWLQL]HGSURWROLWK7KH¿HOGREVHUYDWLRQDQG PLFURVFRSLFDQDO\VLVLQGLFDWHWKDWWKHJDUQLHULWHLQWKH:HVW%ORFNRFFXUVLQWKHWKUHHPRGHV L VOLFN- HQVLGHGIDXOWFRDWLQJLL IUDFWXUH¿OOHGYHLQVDQGLLL PDWULFHVLQFRQJORPHUDWLFSHULGRWLWH:KLOHLQWKH 3HWHDDUHDWKHJDUQLHULWHLVRQO\IRXQGDVYHLQ¿OOLQJIUDFWXUHV5HVXOWVRI;5'DQDO\VLVH[KLELWWKDW JDUQLHULWHIURP6RURDNRLVPDLQO\FRPSRVHGRINHUROLWHSLPHOOLWHWDOFZLOOHPVLWH1LVHUSHQWLQHDQG sepiolite-falcondoite series. Nickel content of the garnierite samples studied by means of XRF methods UDQJHVIURPWR ZW7KHZLGHYDULDWLRQRI1LFRQWHQWLQWKHDQDO\]HGJDUQLHULWHVDPSOHVLVOLNHO\ FDXVHGE\WKHSUHVHQFHRIJDQJXHPLQHUDOVSDUWLFXODUO\TXDUW]VLOLFDDQGWUDFHDPRXQWRILURQR[LGHV Keywords: garnierite, peridotite, kerolite, sepiolite, nickeliferous laterite
SARI Suatu penelitian bijih Ni-Mg hidrous silikat yang dikenal dengan “garnierit” pada endapan nikel laterit Soroako telah dilakukan dengan menggunakan metode mikroskopi optis, XRD, dan XRF dengan tujuan untuk menguraikan keterdapatan, komposisi mineralogi, dan kimia garnierit. Percontoh garnierit diambil baik dari blok barat maupun Blok Petea. Blok Barat terutama disusun oleh batuan peridotit tak terserpentinisasi, sedangkan Blok Timur yang diwakili oleh daerah Petea ditutupi oleh protolit dengan tingkat serpentinisasi sedang sampai tinggi. Penelitian lapangan dan analisis mikroskopi menunjukkan bahwa garnierit pada blok barat terdapat dalam tiga bentuk yaitu: lapisan tipis pada bidang rekahan dan patahan, sebagai bahan pengisi rekahan atau urat, dan sebagai matriks pada peridotit konglomeratan. Sementara pada Blok Petea, garnierit hanya dijumpai dalam bentuk urat. Hasil analisis XRD menunjukkan bahwa komposisi mineral garnierit Soroako terdiri atas seri kerolit- pimellit, seri talk-wilemsit, Ni-serpentin, dan seri sepiolit-falkondoit. Kadar nikel pada percontoh garnierit yang ditentukan dengan metode XRF memperlihatkan nilai antara 1,8 - 19,2%. Variasi ini mungkin disebabkan oleh keterdapatan mineral gang terutama kuarsa/silika dan sedikit oksida besi. Kata kunci: garnierit, peridotit, kerolit, sepiolit, laterit nikel
Naskah diterima: 03 Januari 2011, revisi terakhir: 12 Maret 2012 1 Corresponding Author: [email protected] Majalah Geologi Indonesia, Vol. 27 No. 1 April 2012: 1-11
INTRODUCTION The objectives of this paper are to describe the mode of occurrence of garnierites, to Nickel laterite deposits contribute to analyze their mineralogical and chemical DURXQGRIZRUOGODQGEDVHGQLFNHO composition of some garnierite samples col- UHVRXUFHVKRZHYHUWKH\RQO\DFFRXQWIRU lected from the Soroako nickeliferous laterite DERXWRIWKHFXUUHQWJOREDOQLFNHO PLQLQJGLVWULFWDQGWRH[SORUHWKHSRVVLEOH SURGXFWLRQV &UXQGZHOOet al., 2011). In- HIIHFWRIVHUSHQWLQL]DWLRQGHJUHHRIXOWUDPD¿F donesia is one of the four largest nickel protolith as host for garnierite mineralization. ODWHULWHRUHSURGXFLQJFRXQWULHVZKHUHWKHVH deposits are mostly located in the eastern UHJLRQVVXFKDV6XODZHVL+DOPDKHUD GEOLOGICAL SETTINGS Gag, and Waigeo Islands. These Nickel- LIHURXVODWHULWHGHSRVLWVLQ6XODZHVLFDQ The rock assemblages occupied Soroako EHIRXQGDW6RURDNR3RPDODD%DKXGRSL DUHDDQGLWVVXUURXQGLQJFDQEHFODVVL¿HG $VHUDDQG%XWRQ7KHVHGHSRVLWVDUHW\SL- LQWRIRXUJURXSV L PHWDPRUSKLFFRPSOH[ FDOO\IRUPHGE\DQH[WHQVLYHO\FKHPLFDO (ii) tectonite rocks, (iii) Mezosoic sedimen- ZHDWKHULQJSURFHVVHVRISHULGRWLWHVLQWKH WDU\VHTXHQFHV LLL 8OWUDPD¿FFRPSOH[HV tropical condition. Nickel laterite ores are and (iv) Tertiary sediments (Simandjuntak FODVVL¿HGLQWRWKUHHW\SHVDFFRUGLQJWRWKH et al., 1991) (Figure 1). GRPLQDWLRQRI1LEHDULQJPLQHUDOV %UDQG 7KHXOWUDPD¿FURFNVDW6RURDNRLVDORZHU et al (OLDV )UH\VVLQHWet al., VHTXHQFHRI(DVW6XODZHVL2SKLROLWH (62 QDPHO\ VLOLFDWHFOD\DQGR[LGH ZKLFKLVPDLQO\FRPSRVHGRIKDU]EXU- RUHV7KHGHSRVLWVZKLFKDUHQRZEHLQJ JLWHZLWKOHVVHUOKHU]ROLWHDQGORFDOO\GXQLWH H[SORLWHGIURP6RURDNRLQFOXGHQLFNHO (Kadarusman et al (62LVRQHRI VLOLFDWHVZKHUHJDUQLHULWHLVWKHSULQFLSDO WKHODUJHVWRSKLROLWHPDVVLYHLQWKHZRUOG Ni-bearing materials. DORQJZLWK2PDQDQG3DSXD1HZ*XLQHD Garnierite is a collective term for Ni-Mg (Monier et al., 1995). It covers an area of ap- 2 hydrous silicate minerals that is commonly SUR[LPDWHO\NP ZLWKDWKLFNQHVVRI used by mine geologists. It is characterized DERXWP7KHGLVWULEXWLRQRIPD¿FDQG E\JUHHQFRORXUQRQVZHOOLQJDQGKLJK1L XOWUDPD¿FURFNVLQHDVWDQGVRXWKHDVWDUPV content (Proenza et al., 2008). Garnierite RI6XODZHVLLVIRXQGDVLVRODWHGEORFNVDORQJ is eventually not a mineral approved by WKHZHVWHUQFRDVWRI%RQH*XOIDQGHDVWFRDVW RI7ROR*XOIH[WHQGLQJWR%DWXL0RXQWDLQWR &RPPLVVLRQRI1HZ0LQHUDODQG0LQHUDO the north (Surono and Sukarna, 2001). Names (CNMMN), but it occurs as intimate PL[WXUHVRIWZRRUPRUHRIWKHIROORZ- In Soroako and Petea areas that have been ing minerals: serpentine, talc, sepiolite, H[SORUHGLQPRUHGHWDLOE\37,1&2 QRZ VPHFWLWHDQGFKORULWH%ULQGOH\DQG+DQJ PT. Vale Indonesia), the rocks commonly (1973) suggested that many garnierites are VKRZFRDUVHJUDLQHGZLWKS\UR[HQH EURQ]- WKHPL[WXUHVEHWZHHQ OD\HUVLOLFDWHV LWHHQVWDWLWH XVXDOO\VKRZLQJXSDVODUJH (serpentine-like phase) and 2 : 1 layer sili- bronze-colour crystals. With the increas- FDWH WDOFOLNHSKDVH ZLWKEDVDOVSDFLQJRI ing degree of serpentinization, the colour 7 Å and 10 Å respectively. Recent studies of the rock generally gets darker (Ahmad, RIJDUQLHULWHPLQHUDORJ\DQGFKHPLVWU\ZHUH 2OLYLQHLVSUHGRPLQDQWPLQHUDOVZLWK reported by Wells et al. (2009) and Tauler VPDOOHUDPRXQWV XSWR RIRUWKRS\- et al. (2009). UR[HQHDQGOHVVHUDPRXQWV XSWR RI
2 Characteristics and the Occurrence of “Garnierite” from the Soroako Nickeliferous Laterite Deposits, Sulawesi, Indonesia (Sufriadin et al.)
121o 05’ E 121o 15’ E 121o 25’ E 121o 35’ E 121o 45’ E o 2 25’ S 2 25’ o 2 25’ S 2 25’ Nuha
Matano Lake Petea 0 200 Km Soroako Legend o 2 35’ S 2 35’
o Mahalona Lake
2 35’ S 2 35’ Surfical Deposits
Larona Formation Malili Wasuponda Wowondula Tomata Formation
Matano Formation Tawuti Lake
o Ultramafic Complex 2 45’ S 2 45’ o 2 45’ S 2 45’ Wasuponda Melange
Masiku Formation
Lohia Town and village
0012 km Fault and lineament
o o o o o Sample location 121 05’ E 121 15’ E 121 25’ E 121 35’ E 121 45’ E
)LJXUH6LPSOL¿HGJHRORJLFDOPDSRI6RURDNR$UHD PRGL¿HGDIWHU6LPDQGMXQWDNet al., 1991).
FOLQRS\UR[HQH7KHUDWLRRIRUWKRS\UR[HQH :HVW%ORFNDQGRWKHU¿YHVDPSOHVWDNHQ WRFOLQRS\UR[HQH 2S[ &S[ LVJHQHUDOO\ IURP3HWHDEORFN6DPSOHVZHUHDQDO\]HG JUHDWHUWKDQWZR7KHRULJLQDORSDTXHPLQ- using optical microscopy, X-ray diffractom- HUDOVLQFOXGHFKURPLWH DERXW ZKLOH HWU\ ;5' DQG;UD\ÀXRUHVFHQFH ;5) VHFRQGDU\PDJQHWLWHLQZHOOVHUSHQWLQL]HG spectroscopy. URFNVFDQUHDFKXSWRDQGLVORFDOL]HG in thin veinlets or along the edges of relic 0LFURVFRSLFREVHUYDWLRQRIWKHVDPSOHVZDV olivine crystals, or distributed as dissemi- SHUIRUPHGXQGHUWUDQVPLWWHGDQGUHÀHFWHG QDWLRQV %DELQHDX 7KHPDJQHWLF light mode by means of Nikon Eclipse LV susceptibility of the rock and the degree of 32/PLFURVFRSH0LQHUDORJLFDODQDO\- serpentinization are correlated. VLVXVLQJ;5'WHFKQLTXHZDVFDUULHGRXWE\ a Rigaku RINT 2000 X-ray diffractometer 7KHXOWUDPD¿FURFNVDOVRVKRZVLJQVRIH[- ZLWKLQFLGHQW&X.ĮUDGLDWLRQDWN9DQG tensive deformation on the basis of crystal P$7KHSDWWHUQVRIGLIIUDFWLRQZHUH IDEULFZLWKLQWKHYLFLQLW\RIIDXOWVSDUWLFX- REWDLQHGE\VFDQQLQJSRZGHUVIURPo larly major thrust faults in the peripheral șZLWKVFDQQLQJVWHSDWo and counting DUHDVWKDWVHSDUDWHWKHXOWUDPD¿FURFNVIURP time 4o/minute. Whole rock chemical analy- the surrounding sediments. VLVRISRZGHUVDPSOHVSUHSDUHGLQYLEUDWLQJ PLOORQSUHVVHGSHOOHWVZDVSHUIRUPHGE\ a Rigaku RIX 3100 X-ray fluorescence SAMPLES AND METHODS VSHFWURPHWHUZLWK;UD\WXEHRSHUDWHGDW N9DQGP$$OOWKHVHDQDO\VHVZHUH Fourteen garnierite samples have been col- conducted at Laboratory of Economic Geol- OHFWHGIURPPLQHVLWHVGXULQJWKH¿HOGZRUN ogy, Department of Earth Resources Engi- They comprise eight samples gathered from neering, Kyushu University, Japan.
3 Majalah Geologi Indonesia, Vol. 27 No. 1 April 2012: 1-11
RESULTS AND DISCUSSION JHQHUDOO\H[KLELWSDOHJUHHQFRORXU¿EURXV and soft materials (Figure 2c). They can be The Occurrence and Microscopic Features WUDFHGDORQJWKHIDXOWSODQHVZKHUHVWULDWLRQV are also common to be found at Ni laterite 2QWKHEDVLVRIWKH¿HOGDSSHDUDQFHRI mines. In the case of fault planes that formed WKHJDUQLHULWHVLQFOXGLQJFRORUWH[WXUHDQG at saprolite zones closed to bedrocks, they crosscutting relationship, their occurrences DUHXVXDOO\FRDWHGZLWK¿EURXVYHLQVWKDW may be distinguished into three types: (i) QRUPDOO\JURZRQWKHURFNVGXULQJWHQVLRQ WKLQOD\HUJDUQLHULWHZLWKLQIUDFWXUHVMRLQWVRU crack opening (crack seal mechanism). In VOLFNHQVLGHGIDXOWFRDWLQJ LL IUDFWXUHV¿OOLQJ JHQHUDOJDUQLHULWHVDUHPRUHH[WHQVLYHRF- materials or veins, and (iii) matrices on peri- FXUULQJLQWKHZHVWEORFNWKDQLQWKH3HWHD dotitic conglomerate (Figure 2). Garnierites block. Garnierite is also found as cements/ LQWKH6RURDNR:HVW%ORFNFRPPRQO\VKRZ matrices in fault gouges or as garnierite medium green colour and they appear as thin matrices in peridotitic conglomerate (Figure - OD\HUV )LJXUHD RUIUDFWXUH¿OOHGYHLQV*DU G ,WRFFXUUHGZKHQ1LVDWXUDWLRQUHDFKHG nierite also formed as en echelon vein arrays previously formed the brecciation zone. The GHYHORSHGRQZHDWKHUHGSHULGRWLWH )LJXUH presence of garnierite clasts indicate tectonic E ZKHUHDVLQWKH3HWHD%ORFNJDUQLHULWHV remobilization of the veins.
a 20 cm b 10 cm
c 20 cm d 10 cm
Figure 2. Field appearances of garnierite ores in Soroako. a. garnierite occurs as slickensided fault coating on ZHDWKHUHGSHULGRWLWHDW.RQGH+LOO EJDUQLHULWHIRUPHGDVHQHFKHORQYHLQDUUD\VRQZHDWKHUHGSHULGRWLWHDW 6XPDVDQJ+LOO F1LULFKVHSLROLWHYHLQZLWKSDOHJUHHQFRORURQKLJKO\ZHDWKHUHGVHUSHQWLQL]HGSHULGRWLWHDW 3HWHD%ORFN G0HGLXPWRGDUNJUHHQJDUQLHULWHDVPDWULFHVRQFRQJORPHUDWLFSHULGRWLWHDW:DZRQR+LOO
4 Characteristics and the Occurrence of “Garnierite” from the Soroako Nickeliferous Laterite Deposits, Sulawesi, Indonesia (Sufriadin et al.)
Results of microscopic analysis indicate Mineralogy WKDWPRVWJDUQLHULWHVKRZFROORIRUPEDQG- Result of XRD analysis reveals that garnier- LQJZLWKFRQFHQWULFJURZWKRUSDUDOOHOZLWK LWHVIURP6RURDNRKDYHZLGHUDQJHYDULDWLRQ alternating light and dark bands (Figure 3a). LQPLQHUDORJ\ 7DEOH KRZHYHUWKH\FRP- ,QWKHIHZDQDO\]HGVDPSOHV¿QHJUDLQHG PRQO\WHQGWREHWKHPL[WXUHVEHWZHHQWDOF crystals of magnetite have been found to be OLNHSKDVHVDQGVHUSHQWLQHOLNHSKDVHV7ZR GLVSHUVHGLQSDUDOOHOZLWKEDQGGLUHFWLRQV series of talc like-phases have been identi- (Figure 3b). Vuggy quartz or silica veins are ¿HGZLWKLQWKHVWXGLHGVDPSOHVQDPHO\ VRPHWLPHVSUHVHQWDVIUDFWXUH¿OOLQJDQGWKH\ NHUROLWHSLPHOOLWHVHULHVZKLFKLVLQGLFDWHG crosscut or parallel to the colloform banding E\WKHSUHVHQFHRIWKHEURDGZLWKVWURQJ ZLWK¿EURXVQHWZRUN )LJXUHF 7KH¿EURXV EDVDOVSDFLQJDWc ZKHUHDVWKHUHÀHF- materials are common features observed WLRQLQWHQVLW\ZLWKEDVDOVSDFLQJDW cLV microscopically developed on the garnierite DGLDJQRVWLFSHDNRIWDOFZLOOHPVHLWHVHULHV VDPSOHVIURP3HWHD%ORFN )LJXUHG 1LVHUSHQWLQHVDUHLQGLFDWHGE\UHÀHFWLRQ
void
Magnetite
Ker-srp mixture aA 0.20.2 mm mm bB 0.2 mmmm
Fibrous Ni sepiolite
Silica
Fibrous Ni -Srp
cC 0.20.2 mm dD 0.4 mm
)LJXUH3KRWRPLFURJUDSKVRIVHOHFWHGJDUQLHULWHVDPSOHVIURP6RURDNRD*DUQLHULWHVKRZLQJWKHFRQFHQWULF FROORIRUPEDQGV EDOWHUQDWLQJEDQGVRINHUROLWHSLPHOLWHDQG1LVHUSHQWLQHZLWK¿QHJUDLQHGPDJQHWLWHFU\V- WDOV EODFN FWKHODWHIRUPHGYXJJ\TXDUW]VLOLFDYHLQFURVVFXWWKH¿EURXV1LULFKVHUSHQWLQH DQGG1LULFK VHSLROLWHGLVSOD\LQJ¿QHO\¿EURXVDJJUHJDWHGHYHORSHGRQVHUSHQWLQL]HGSHULGRWLWH
5 Majalah Geologi Indonesia, Vol. 27 No. 1 April 2012: 1-11
Table 1. Mineralogical Composition of Soroako Garnierite Samples analyzed by XRD Method
Sample Code Minerals/ Garnierite from Soroako West Block Garnierite from Petea Block phases KO1 SU2 WW3 WW-4 KO4 IN1 KR1 AN4 SG4 PG1 PG3 PG4 AS6 PB5 Kerolite- pimellite - ++ +++ ++ +++ - ++ - + - - +++ - ++ Talc- ZLOOHPVHLWH ++ - - - - +++ - - - - - ++ - +++ Ni-serpentine + + ++ ++ ++ + +++ + +++ +++ +++ - +++ - Smectite - - - - - ++ - +++ ------Quartz - +++ - +++ ++ ++ - - + + + + + - 3\UR[HQH ++-++----+------,URQR[LGHV --- -+-+-+----+ 1RWHV PDMRU !ZW PLQRU ±ZW WUDFH ZW QRWGHWHFWHG at 7.10Å and 7.33Å, possibly chrysotile ZKHUH0J U c KDVUHODWLYHO\VLPLODU RUOL]DUGLWHHQGPHPEHUV+RZHYHULWLV DWRPLFVL]HZLWK1L U c ,WLVWKHUHIRUH GLI¿FXOWWRGLVFULPLQDWHVHUSHQWLQHVSHFLHV H[SHFWHGWKDW1L2+ZRXOGHDVLO\UHSODFHVIRU GXHWRWKHVLPLODUUHÀHFWLRQDQGJHQHUDOO\ VL[FRRUGLQDWH0J2+ (Faye, 1974). Ratio of GLIIUDFWLRQSDWWHUQVVKRZRYHUODSSLQJ0RVW 1L0J2ZRXOGGHWHUPLQHWKHFRPSRVLWLRQDO analyzed samples indicate the presence of limit that can be used to provide the termi- TXDUW]RUVLOLFDZLWKUHÀHFWLRQDWc7KH nology of garnierite solid – solution series. LURQR[LGHVSRVVLEO\PDJQHWLWHDUHSUHV- )RUH[DPSOH1LDQG0J2FRQWHQWRIVDPSOH HQWLQIHZVDPSOHVLQWUDFHDPRXQW2WKHU $6DUHDQGZWUHVSHFWLYHO\ PLQHUDOVVXFKDV1LVPHFWLWHDQGS\UR[HQH %HFDXVH1L0J2UDWLRRIWKLVVDPSOHLV ZHUHDOVRGHWHFWHGLQWUDFHDPRXQWV7KH more than 0.5, then the better match for the strongest lines around 12 Å observed from QDPHZRXOGEHIDOFRQGRLWH6LPLODUO\WKH 3HWHDVDPSOHVFOHDUO\H[KLELWWKHH[LVWHQFH 1L0JK\GURXVVLOLFDWHRIVDPSOH.2 of sepiolite-falcondoite series. could be assigned to pimellite, a solid solu- WLRQRINHUROLWHZKLFKLVDQDORJXHWRK\GURXV Whole Rock Chemistry talc. Nickel concentrations of all samples are KLJKO\YDULDEOHUDQJLQJEHWZHHQZW Chemical compositions of garnierite sam- DQG ZW ples determined by XRF are presented in
7DEOH7KH6L22DQG0J2DUHWKHWZR 7KH)H2FRQWHQWRIVDPSOHVIURP6RURDNR GRPLQDQWPDMRUR[LGHVUDQJLQJIURPWR ZHVWEORFNUDQJHVEHWZHHQDQG ZW ZWDQGWRZWUHVSHFWLYHO\ DYZW ZKLOHVDPSOHVIURP3HWHDWHQG
9DULDWLRQRI6L22 is dependent on mineral- WREHORZHU ZW H[FHSWIRUVDPSOH ogical composition particularly the presence 3%KDYLQJKLJKHUFRQWHQW ZW 7KH of quartz or amorphous silica. In addition, presence of tiny magnetite crystals likely the differences in layer silicates of minerals can contribute to increase the iron concen- containing in garnierites may also contribute tration in analyzed samples.
WRLQFUHDVH6L22 concentrations. The concentration of Al223 in both Soroako 0DJQHVLXPWHQGVWRVKRZQHJDWLYHFRU- ZHVWEORFNDQG3HWHDJDUQLHULWHVDPSOHVDUH UHODWLRQZLWKQLFNHO7KLVFDQEHH[SODLQHG JHQHUDOO\ORZ ZW ZLWKH[FHSWLRQRI E\WKHH[FKDQJHUHDFWLRQRIWKRVHHOHPHQWV WZRVDPSOHVIURP:HVW%ORFNQDPHO\.2
6 Characteristics and the Occurrence of “Garnierite” from the Soroako Nickeliferous Laterite Deposits, Sulawesi, Indonesia (Sufriadin et al.)
Table 2 Whole Rock Chemistry of Garnierite Samples from Soroako determined by XRF.
Sample ID Composition Unserpentinized Peridotite Serpentinized Peridotite (wt %) (West Block) (Petea Block) KO-1 SU-2 WW-3 WW-4 KO-4 IN-1 KR-1 AN-4 SG4 PG-1 PG-3 AS-6 PG-4 PB-5
6L22 44.95 50.08 48.39 48.48 50.07 49.19
7L22 0.01 0.01 0.01
Al223 23.28 0.10 0.20 0.42 0.49 0.11 11.21 0.04 0.05 0.10 0.87 0.11 0.24 )H2 1.80 1.45 3.70 2.98 9.27 1.87 3.93 0.42 0.28 0.40 0.15 0.28 0Q2 0.03 0.02 0.07 0.05 0.14 0.02 0.20 0.01 0.01 0.07 0.11 0J2 22.15 19.84 28.70 15.82 35.79 20.81 20.81 8.87 31.94 &D2 4.33 0.02 0.09 0.01 0.43 0.02 0.01 0.02 0.02 0.03
Na22 0.13 0.02
K22 0.02 0.02 0.03 0.01 0.01 0.01 0.01 0.01 0.01 0.01
P225 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01
H22 8.94 10.71 13.28 7.74 10.38 9.09 23.40 24.57 11.80 10.59 Total oxides 96.86 91.08 89.63 97.23 80.15 91.85 89.41 87.64 97.99 94.62 95.10 84.93 84.43 95.67 Zn 0.05 0.14 0.17 0.03 0.41 0.12 0.17 0.25 0.02 0.01 0.07 0.08 0.49 0.05
Cr 0.04 0.03 0.11 0.08 0.30 0.05 0.05 0.25 0.01 0.01 0.17
Ni 2.96 8.73 10.10 2.66 19.11 7.90 10.19 12.01 1.75 5.25 4.75 14.85 14.68 4.10
Co (ppm) 24 78 59 157 28 87 20 191 5 7 44 104
6L220J2 4.10 3.29 3.54 3.53 2.41 8.28 7.75 Ni/ 0.18 0.31 0.12 0.58 0.30 0.43 0.05 0.20 0.19 0.11 1L0J2 )H2DVVXPHGDVWRWDOLURQ
DQG$1%RWKRIWKHVHVDPSOHVFRQWDLQ anomalous Al223 RIZWDQG 0RVWO\VDPSOHVDOVRFRQWDLQORZ&D2 ZWUHVSHFWLYHO\$FFRUGLQJWR;5'GDWD FRQFHQWUDWLRQH[FHSWIRUVDPSOH.2 VDPSOH.2LVFRPSRVHGRIWKHPL[WXUHEH- ZW DQG$1 ZW 7KH WZHHQ1LULFKVHUSHQWLQH OL]DUGLWHQHSRXLWH ¿UVWVDPSOHSRVVLEO\FRQWDLQVUHPQDQWRI VHULHV 1LNHUROLWHDQGS\UR[HQHUHOLF ZKLOH &DULFKS\UR[HQH7KHKLJKHU&D2FRQWHQW sample AN-4 contains predominantly Ni- LQVDPSOH$1FRXOGEHDVVRFLDWHGZLWK ULFKVPHFWLWHZLWKPLQRUVHUSHQWLQH7KH VPHFWLWHVWUXFWXUH2WKHUPDMRUR[LGHVVXFK DV7L220Q21D22DQG.22DUHYHU\ORZ high Al223FRQWHQWRIVDPSOH.2PD\EH related to the presence of “brindleyite”, a ZW nickel-rich aluminous serpentine (Maksi- Water content of garnierite is highly vari- PRYLFDQG%LVK ,QWKHFDVHRIVDPSOH DEOH7KHDYHUDJHRI/2,IURP:HVW%ORFN
AN-4, the high concentration of Al223 could VDPSOHV LVPXFKORZHUWKDQ3HWHD be derived from decomposition of Al-rich VDPSOHV 7KHVHYDOXHVDUHGHSHQ- smectite (beidellite) and partly originated dent on mineral proportions in the samples. from serpentine. The presence of anhydrous phases such as
7 Majalah Geologi Indonesia, Vol. 27 No. 1 April 2012: 1-11
TXDUW]DQGS\UR[HQHFOHDUO\GHFUHDVHWKH LQWKHORZHUSUR¿OHGXHWRWKHFKDQJHVLQS+ PRLVWXUHFRQWHQW,QDGGLWLRQZDWHUFRQWHQW RIVROXWLRQ$WWKHXSSHUSUR¿OHZHDWKHULQJ of talc and serpentine is different. Pure talc VROXWLRQLVVOLJKWO\DFLGLF S+ +RZHYHU
ZW+22 KDVPXFKORZHUWKDQVHUSHQ- DWWKHORZHUSUR¿OHWKHS+RIVROXWLRQLV
WLQH ZW+22 7KHH[WUDRUGLQDULO\ VOLJKWO\DONDOLQH S+! GXHWRWKHURFNZD- high moisture content of samples PG1 (23.4 ter interaction (Taylor and Eggleton, 2001). DQG3* IURP3HWHD%ORFN The occurrence of quartz replacement may DUHLQJRRGDJUHHPHQWZLWKWKHSUHVHQFHRI EHUHVXOWHGIURPDSHULRGLFGU\ZHWFRQGL- sepiolite (Weaver and Pollard (1973). tion or from a retarded drainage in a more acid environment (Golightly, 1981). During Precipitation of Garnierite the dry season, silica concentrations are very Soroako nickeliferous laterite deposits are high (Harder, 1977). The pH of solution is FODVVL¿HGDV1L0JK\GURXVVLOLFDWHW\SH VOLJKWO\DFLGLFZKHQLWFRQWDPLQDWHZLWK and the principal Ni-bearing phases are humid substance, therefore the precipitation hydrated silicates occurring in the form of of silica is possible. veins, fracture coating, and clasts or matri- *DUQLHULWHDWWKH3HWHD%ORFNLVFKDUDFWHU- ces components of the breccias. They are L]HGE\WKLQDQGGLVFRQWLQXRXVYHLQVZKLFK H[WHQVLYHO\GHYHORSHGRQKLJKO\IUDFWXUHG are mainly composed of sepiolites. Their of unserpentinized peridotites. occurrences are rare and generally hosted )LHOGREVHUYDWLRQDQGWH[WXUDOHYLGHQFHV LQVOLJKWO\ZHDWKHUHGVHUSHQWLQL]HGSHULGR- LQGLFDWHWKDWJDUQLHULWHVDW6RURDNRZHVW tite. Sepiolite-falcondoite has been found EORFNKDYHEHHQSUHFLSLWDWHGDWOHDVWLQWZR WREHDVVRFLDWHGZLWKDPRUSKRXVVLOLFD HSLVRGHV7KHHDUO\IRUPHGYHLQW\SHZDV rather than quartz, indicating more alkaline RULJLQDWHGIURPVROXWLRQVGHULYHGE\ZHDWK- HQYLURQPHQWDOIRUPDWLRQ %LUVR\ HULQJSURFHVVPDLQO\RI1LEHDULQJROLYLQH Neoformation of sepiolite is most favored ZKHUHDVWKHODWHIRUPHGFODVWVPDWULFHVW\SH ZKHUHWKHZHDWKHULQJVROXWLRQLVVOLJKWO\ could be originated from dissolution of the alkaline (pH: ~8.0 to ~9.5), high (Mg+Si)/ early-formed vein type and other Ni-bearing $OUDWLRDQGORZ P&22 (Galan and Pozo, phases. 8 Characteristics and the Occurrence of “Garnierite” from the Soroako Nickeliferous Laterite Deposits, Sulawesi, Indonesia (Sufriadin et al.) under pressure are more susceptible to dis- series are the main Ni-bearing minerals solve than unstressed minerals (Cluzel and LGHQWL¿HGLQJDUQLHULWHVDPSOHV7KHSUHV- Vigier, 2008). Transport of material from ence of quartz or amorphous silica in the dissolution site to precipitation site may take PRVWDQDO\]HGVDPSOHVFDQKDYHVLJQL¿FDQW SODFHE\GLIIXVLRQDOPDVVWUDQVIHU %RQVDQG contribution to the high silica-magnesia Jessel, 1997). ratio of mined ores in particularly of the In general, the scarcity of garnierites occur- :HVW%ORFN ULQJDWWKH3HWHD%ORFNDVFRPSDUHGWRWKH Nickel concentrations of all analyzed sam- :HVW%ORFNPD\LQSDUWEHFRQWUROOHGE\ SOHVDUHKLJKO\YDULDEOHUDQJLQJEHWZHHQ differences in physico-chemical properties ZWDQG ZW7KH\VXJJHVWWKH RIXOWUDPD¿FSURWROLWKDQGWKHLUZHDWKHULQJ presence of gangue minerals as impurities products. Peridotite bedrocks at Soroaoko PDLQO\TXDUW]VLOLFDDQGLURQR[LGHV ZHVWEORFNDUHXQVHUSHQWLQL]HG7KHVHURFNV are characterized by medium- to coarse- Precipitations of garnierite are not only JUDLQHGDQGPDVVLYH+RZHYHUWKHLUKLJKHU controlled by environmental conditions IUDFWXUHLQWHQVLWLHVDUHSURQHWRZHDWKHULQJ S+(KJURXQGZDWHUFKHPLVWU\ EXWRWKHU thereby released the Ni ion into solution. factors such as lithology (serpentinization 7KHIUDFWXUHVDUHDOVRDFWLQJDVSDWKZD\VWR degree of protolith) and structures (fracture DOORZWKHUDSLGSHUFRODWLRQRI1LVDWXUDWHG intensities and tectonic reactivation) may VROXWLRQGRZQZDUGDQGSUHFLSLWDWHDWWKH also be responsible for the rates and intensi- EDVHWRIRUP1LK\GURXVVLOLFDWHYHLQVZKHUH ties of garnierite formation. condition becomes slightly alkaline. 2QWKHFRQWUDU\WKHEHGURFNVDW3HWHD%ORFN ACKNOWLEDGEMENTS typically consist of the highly serpentinized SHULGRWLWHVZLWK¿QHJUDLQHGWH[WXUHDQG 7KHDXWKRUVZRXOGOLNHWRDFNQRZOHGJH37,1&2 VKRZLQJDEHWWHUFRKHVLRQ 3HOOHWLHU 0DQDJHPHQW QRZ379DOH,QGRQHVLD IRUWKH This properties may preclude precipitation permission to collect samples. Special thanks are of garnierite veins because Ni2+LQZHDWKHU- addressed to Prof. Koichiro Watanabe at the De- partment of Earth Resources Engineering, Kyushu ing solution is readily adsorbed onto crystal University for providing access in using laboratory 2+ surfaces or substitutes for Mg in octahedral facilities. Thanks are also due to Dr. Ade Kadarus- sites of serpentine structures. PDQIRUYDOXDEOHVXJJHVWLRQVGXULQJWKH¿HOGZRUNV 7KLVVWXG\KDVEHHQVXSSRUWHG¿QDQFLDOO\E\-$662 Short Terms Research Scholarship at Kyushu Uni- versity, Japan. CONCLUSIONS 2QWKHEDVLVRISUHYLRXVGLVFXVVLRQWKH REFERENCES FRQFOXVLRQVFDQEHZLWKGUDZQDVIROORZV $KPDG:0LQH*HRORJ\DW37,1&2 Garnierite at Soroako occur as thin layer or Unpublished Training Manual, 118p. VOLFNHQVLGHGIDXOWFRDWLQJDVIUDFWXUH¿OO- ing materials or veins, and as matrices in %DELQHDX-3HWURJUDSK\RIURFNVDPSOHV collected in Petea, Mahalona, and Konde areas, peridotitic conglomerate. 6RURDNR6XODZHVLUnpublished Internal Memo. Talc-like phases (kerolite-pimelite and talc- %LUVR\5)RUPDWLRQRIVHSLROLWHSDO\JRUVNLWH ZLOOHPVHLWHVHULHV VHUSHQWLQH OL]DUGLWH and related minerals from solution. Clays and Clay nepouite series), and sepiolite-falcondoite Minerals S 9 Majalah Geologi Indonesia, Vol. 27 No. 1 April 2012: 1-11 %RQV3'DQG-HVVHO0: ([SHULPHQWDO Harder, H., 1977. Clay mineral formation under VLPXODWLRQRIWKHIRUPDWLRQRI¿EURXVYHLQVE\ORFDO- ODWHULWLFZHDWKHULQJFRQGLWLRQVClay Minerals, 12, ised dissolution-precipitation creep. Mineralogical p.281-288. MagazineS Kadarusman, A. Miyashita, S. Maruyama, S. Par- %UDQG1:%XWW&50DQG(OLDV0 NLQVRQ&'DQG,VKLNDZD$3HWURORJ\ 1LFNHOODWHULWH FODVVL¿FDWLRQDQGIHDWXUHVAGSO geochemistry and paleogeographic reconstruction of Journal of Australian Gology & Geophysics, 17 WKH(DVW6XODZHVL2SKLROLWH,QGRQHVLDTectonophys- (4), p.81- 88. ics, 392, p.55-83. %ULQGOH\*:DQG+DQJ37 7KHQDWXUHRI 0DNVLPRYLF=DQG%LVK'/ %ULQGOH\LWHD garnierites - I: Structures, chemical compositions nickel-rich aluminous serpentine mineral analogous and color characteristics. Clays and Clay Minerals, to berthierine. American MineralogistS 21, p.27-40. Monnier, C., Girardieau, J., Maury, R.C., and Cotton, %ULQGO\*:%LVK'/DQG:DQ+0 7KH - %DFNDUFEDVLQRULJLQIRUWKH(DVW6XODZHVL nature of kerolite, its relation to talc and stevensite. 2SKLROLWH(DVWHUQ,QGRQHVLDGeology 23, p.851-854. Mineralogical Magazine, 41, p.443-452. 3HOOHWLHU%* 6HUSHQWLQHVLQQLFNHOVLOLFDWH &OX]HO'DQG9LJLHU%6\QWHFWRQLFPR- RUHIURP1HZ&DOHGRQLD 0HOERXUQHAustralasian ELOLW\RIVXSHUJHQHQLFNHORUHVRI1HZ&DOHGRQLD Institute of Mining and Metallurgy Publication Se- 6RXWKZHVW3DFL¿F (YLGHQFHIURPJDUQLHULWHYHLQV ries, S and faulted regolith. Resources Geology, 58 (2), S 3URHQ]D-$/HZLV)-*DOL67DXOHU(/DE- UDGRU00HOJDUHMR-&/RQJR)DQG%ORLVH &UXQGZHOO).0RHW065DPDFKDQGUDQ9 G., 2008. Garnierite mineralization from Falcondo Robinson, T.E., and Devenport, W.G., 2011. Extrac- Ni-laterite deposits (Dominican Republic). Macla, 9. tive metallurgy of nickel, cobalt, and platinum-group metals. Elsevier, Amsterdam. 6LPDQGMXQWDN725XVPDQD(6XURQRDQG6X- SDQGMRQR-% Peta Geologi Lembar Malili, Elias, M., 2002. Nickel laterite deposits a geological Sulawesi. Pusat Penelitian dan Pengembangan Ge- RYHUYLHZUHVRXUFHVDQGH[SORLWDWLRQ +REDUW8QL- RORJL%DQGXQJ versity of Tasmania. Centre for Ore Deposit Research Special Publication, 4, p.205-220. 6RQJ<0RRQ+6DQG&KRQ+7 1HZ occurrence and characterization of Ni-serpentines )D\H*+ 2SWLFDODEVRUSWLRQVSHFWUXPRI LQWKH.ZDQJFKHRQDUHD.RUHDClay Minerals, 30, Ni2+ in ganierite: A discussion. Canadian Mineralo- p.211-224. gist, 12, p.389-393. Surono and Sukarna, D.7KH(DVWHUQ6XODZHVL )UH\VVLQHW3+%XWW&500RUULV5&DQG 2SKLROLWH%HOW(DVWHUQ,QGRQHVLD$5HYLHZRILWV 3LDQWRQH32UHIRUPLQJSURFHVVHVUHODWHG RULJLQZLWKVSHFLDOUHIHUHQFHWRWKH.HQGDULDUHDIn: WRODWHULWLFZHDWKHULQJEconomic Geology 100th Hartono, U. (Eds.), 2¿ROLWGL6XODZHVL+DOPDKHUD Anniversary VolumeS dan Kalimantan, Publikasi Khusus, 28, Pusat Pene- OLWLDQGDQ3HQJHPEDQJDQ*HRORJL%DQGXQJ Galan, E. and Pozo, M., 2011. Palygorskite and sepiolite deposits in continental environments. Taylor, G. and Eggleton, R.A., 2001. Regolith geol- Description, Genetic Patterns and Sedimentary Set- ogy and geomorphology:LOH\1HZ 10 Characteristics and the Occurrence of “Garnierite” from the Soroako Nickeliferous Laterite Deposits, Sulawesi, Indonesia (Sufriadin et al.) Wells, M.A., Ramanaidou, E.R. Verral, M., and Tes- 11