Research Paper

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Econ. Environ. Geol. 2023; 56(3): 343-363

Published online June 30, 2023

https://doi.org/10.9719/EEG.2023.56.3.343

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Characteristics and Controlling Factors on Nickel Laterite Deposits in Sulawesi, Indonesia

Younggi Choi*, Byounghan Kim

Overseas Exploration Team, Korea Mine Rehabilitation and Mineral Resources Corporation, Wonju 26464, South Korea

Correspondence to : *dudrl@komir.or.kr

Received: March 8, 2023; Revised: April 6, 2023; Accepted: April 25, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

Sulawesi island, as a global producer of nickel resources, is leading the rapid growth of nickel industry of Indonesia. Nickel laterite deposits in Sulawesi was formed by lateritization of the world-scale East Sulawesi Ophiolite (ESO) under the active tectonic setting and tropical rainforest climate. In this paper, exploration cases for nickel laterite deposits in five regions of Sulawesi are reported. Regional characteristics on nickel laterite deposits in Sulawesi are understood based on various exploration activities such as outcrop, trench and pit survey, petrological observation, geochemical analysis, and interpretation of drilling data, etc.. In the northeastern part of ‘Southeast-Arm’, which is a strategic location for nickel industry of Indonesia, ESO is extensively exposed to the surface. In the Morombo and Morowali regions, typical high-grade saprolite-type orebodies with a thickness of 10 to 20 m occur. The cases showed that topographic relief tends to regulate Ni-grade distribution and orebody thickness, and that high grade intervals tend to occur in places where joints and garnierite veins are dense. In the Tinanggea and South Palangga regions in the southern part of the Southeast-Arm, overburden composed of Neogene to Quaternary deposits is a major factor affecting the preservation and profitability of nickel laterite deposits. Despite the overburden, high-grade saprolite-type orebodies composed of Ni-bearing serpentine with garnierite veins occur in a thickness of around 10 m to secure economic feasibility. In contrast, in the Ampana region in the northern part of ‘East-Arm’, low-grade nickel laterite deposits with immature laterite profile was identified, which is thought to be the result of active denudation due to tectonic uplift. Exploration cases in this paper will help to understand characteristics and controlling factors on nickel laterite deposits in Sulawesi, Indonesia.

Keywords Indonesia, Sulawesi, Ni-laterite deposits, laterite profile, exploration factors

인도네시아 술라웨시 니켈 라테라이트 광상의 특성과 광화 규제 요인

최영기* · 김병한

한국광해광업공단 해외조사팀

요 약

인도네시아 술라웨시는 니켈 라테라이트 광상의 세계적인 산출지로 인도네시아 니켈산업의 급속한 성장을 견인하고 있다. 활성경계부 지구조환경과 열대우림기후 그리고, 세계적 규모의 동부 술라웨시 오피오라이트(ESO)로부터 니켈 라테라이트 광상이 형성되었다. 술라웨시에 부존하는 니켈 라테라이트 광상의 특성을 이해하는 일은 니켈자원 탐사에 있어 매우 중요하다. 이 논문에서는 술라웨시 5개 지역에서 수행된 니켈 라테라이트 광상 탐사사례들을 보고한다. 지표지질조사, 트렌치 및 채굴적 단면조사, 암석기재, 전암화학 분석 및 시추탐사자료 해석 등 다양한 탐사활동들을 토대로 술라웨시 니켈 라테라이트 광상에 대한 지역별 특성들을 보고한다. 인도네시아 니켈산업의 요충지인 ‘남동부-암’(Southeast-Arm) 북동부에 위치하는 모롬보와 모로왈리지역에서는 오피오라이트가 광역적으로 분포하고, 전형적인 사프로라이트형 광상이 고품위로 부존한다. 지형기복이 니켈 품위와 광체 기하를 제어하며, 절리와 가니어라이트맥이 조밀한 곳에서 고품위로 산출되는 경향이 있다. 남동부-암 남부 티낭게아와 남팔랑가 지역에서는 신생대 퇴적층으로 구성되는 오버버든(overburden)이 니켈 라테라이트 광상 상위로 놓이므로 탐사 시에 파악해야 할 주요 인자이다. 오버버든에도 불구하고, 가니어라이트맥과 함께 함니켈-사문석류로 구성되는 고품위 사프로라이트형 광체가 10 m 내외 두께로 발달하여 경제성을 확보한다. 이와 달리, ‘동부-암(East-Arm)’ 북부 암파나 지역은 니켈 라테라이트 광상이 저품위로 부존하며, 라테라이트 프로파일이 미성숙하다. 이는 지구조 융기에 따른 삭박률이 니켈 라테라이트 광상의 형성 속도를 앞지른 결과로 생각된다. 이 논문에서 다루어진 탐사사례들은 니켈 라테라이트 광상의 부존특성과 광화 규제요인의 유기적인 상호작용을 보여준다.

주요어 인도네시아, 술라웨시, 니켈 라테라이트 광상, 라테라이트 프로파일, 탐사 인자

Article

Research Paper

Econ. Environ. Geol. 2023; 56(3): 343-363

Published online June 30, 2023 https://doi.org/10.9719/EEG.2023.56.3.343

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Characteristics and Controlling Factors on Nickel Laterite Deposits in Sulawesi, Indonesia

Younggi Choi*, Byounghan Kim

Overseas Exploration Team, Korea Mine Rehabilitation and Mineral Resources Corporation, Wonju 26464, South Korea

Correspondence to:*dudrl@komir.or.kr

Received: March 8, 2023; Revised: April 6, 2023; Accepted: April 25, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

Sulawesi island, as a global producer of nickel resources, is leading the rapid growth of nickel industry of Indonesia. Nickel laterite deposits in Sulawesi was formed by lateritization of the world-scale East Sulawesi Ophiolite (ESO) under the active tectonic setting and tropical rainforest climate. In this paper, exploration cases for nickel laterite deposits in five regions of Sulawesi are reported. Regional characteristics on nickel laterite deposits in Sulawesi are understood based on various exploration activities such as outcrop, trench and pit survey, petrological observation, geochemical analysis, and interpretation of drilling data, etc.. In the northeastern part of ‘Southeast-Arm’, which is a strategic location for nickel industry of Indonesia, ESO is extensively exposed to the surface. In the Morombo and Morowali regions, typical high-grade saprolite-type orebodies with a thickness of 10 to 20 m occur. The cases showed that topographic relief tends to regulate Ni-grade distribution and orebody thickness, and that high grade intervals tend to occur in places where joints and garnierite veins are dense. In the Tinanggea and South Palangga regions in the southern part of the Southeast-Arm, overburden composed of Neogene to Quaternary deposits is a major factor affecting the preservation and profitability of nickel laterite deposits. Despite the overburden, high-grade saprolite-type orebodies composed of Ni-bearing serpentine with garnierite veins occur in a thickness of around 10 m to secure economic feasibility. In contrast, in the Ampana region in the northern part of ‘East-Arm’, low-grade nickel laterite deposits with immature laterite profile was identified, which is thought to be the result of active denudation due to tectonic uplift. Exploration cases in this paper will help to understand characteristics and controlling factors on nickel laterite deposits in Sulawesi, Indonesia.

Keywords Indonesia, Sulawesi, Ni-laterite deposits, laterite profile, exploration factors

인도네시아 술라웨시 니켈 라테라이트 광상의 특성과 광화 규제 요인

최영기* · 김병한

한국광해광업공단 해외조사팀

Received: March 8, 2023; Revised: April 6, 2023; Accepted: April 25, 2023

요 약

인도네시아 술라웨시는 니켈 라테라이트 광상의 세계적인 산출지로 인도네시아 니켈산업의 급속한 성장을 견인하고 있다. 활성경계부 지구조환경과 열대우림기후 그리고, 세계적 규모의 동부 술라웨시 오피오라이트(ESO)로부터 니켈 라테라이트 광상이 형성되었다. 술라웨시에 부존하는 니켈 라테라이트 광상의 특성을 이해하는 일은 니켈자원 탐사에 있어 매우 중요하다. 이 논문에서는 술라웨시 5개 지역에서 수행된 니켈 라테라이트 광상 탐사사례들을 보고한다. 지표지질조사, 트렌치 및 채굴적 단면조사, 암석기재, 전암화학 분석 및 시추탐사자료 해석 등 다양한 탐사활동들을 토대로 술라웨시 니켈 라테라이트 광상에 대한 지역별 특성들을 보고한다. 인도네시아 니켈산업의 요충지인 ‘남동부-암’(Southeast-Arm) 북동부에 위치하는 모롬보와 모로왈리지역에서는 오피오라이트가 광역적으로 분포하고, 전형적인 사프로라이트형 광상이 고품위로 부존한다. 지형기복이 니켈 품위와 광체 기하를 제어하며, 절리와 가니어라이트맥이 조밀한 곳에서 고품위로 산출되는 경향이 있다. 남동부-암 남부 티낭게아와 남팔랑가 지역에서는 신생대 퇴적층으로 구성되는 오버버든(overburden)이 니켈 라테라이트 광상 상위로 놓이므로 탐사 시에 파악해야 할 주요 인자이다. 오버버든에도 불구하고, 가니어라이트맥과 함께 함니켈-사문석류로 구성되는 고품위 사프로라이트형 광체가 10 m 내외 두께로 발달하여 경제성을 확보한다. 이와 달리, ‘동부-암(East-Arm)’ 북부 암파나 지역은 니켈 라테라이트 광상이 저품위로 부존하며, 라테라이트 프로파일이 미성숙하다. 이는 지구조 융기에 따른 삭박률이 니켈 라테라이트 광상의 형성 속도를 앞지른 결과로 생각된다. 이 논문에서 다루어진 탐사사례들은 니켈 라테라이트 광상의 부존특성과 광화 규제요인의 유기적인 상호작용을 보여준다.

주요어 인도네시아, 술라웨시, 니켈 라테라이트 광상, 라테라이트 프로파일, 탐사 인자

    Fig 1.

    Figure 1.Geological map of Sulawesi island, Indonesia (modified after Hall and Wilson, 2000; Kadarusman et al., 2004; Choi et al., 2021). Red circles indicate the areas of studied nickel laterite deposits.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 2.

    Figure 2.Geology of Morombo area in the northeast part of 'Southeast-Arm' of Sulawesi. Photograph (A) and photomicrograph (B) of serpentinite. (C) Vertical to deeply dipping joints. (D) Deeply dipping conjugate veins. Note the sigmoidal shape of veins. (E) Syn-kinematic fibrous serpentine vein. (F) Stereogram of joints and veins.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 3.

    Figure 3.Selected photographs for pit survey of the nickel laterite deposits in Morombo area. (A) Panoramic view for the studied pit. (B) Boundary between limonite and saprolite. (C) Corestones in upper part of saprolite zone. (D) Fracture-fill and/or coating of garnierite and silica. (E) Highly connected and densely spaced fractures filled with garnierite.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 4.

    Figure 4.Vertical geochemical variations for Survey Line-1 and -2 for the studied pit in Morombo area.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 5.

    Figure 5.Representative photographs of fault zones in Morowali area in the northeast part of 'Southeast-Arm' of Sulawesi. (A) Highly fractured fault damage zone. (B) Fault core mostly composed of fault gouge.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 6.

    Figure 6.Selected photographs of nickel laterite deposits in Morowali area. (A) Panoramic view for the studied test pit. Note the well developed laterite profile zones. (B) Ferruginous cap showing vermicular or honeycomb texture. (C) Limonite zone. (D) Yellowish saprolite showing stockworks structure. (E) Fibrous serpentine filling fracture.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 7.

    Figure 7.Interpreted mineralized zone for nickel laterite deposits in Morowali area. (A) Topographic map showing locations of drill holes and cross sections. GPS coordinate is based on WGS84 (datum) and UTM zone 5 (grid). (B, C) Interpreted cross sections. Note the vertical exaggeration.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 8.

    Figure 8.Topography and geology of the nickel laterite deposits in Tinanggea area in the southern part of 'Southeast-Arm' of Sulawesi. (A) Elevation map. Note WNW-ESE structural trend. GPS coordinate is based on WGS84 (datum) and UTM zone 5 (grid). (B) Interpreted cross section (A-A’). N-Q: Neogene-Quaternary deposits. (C) Outcrop photograph of the Quaternary alluvium. Men in white circle for scale. (D) Exposure of parent rock (ultramafic rock).
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 9.

    Figure 9.Selected photographs for trench survey. (A) Test Trench-1. (B) Test Trench-2. (C) Red laterite. (D) Yellow laterite. (E) Earthy garnierite. (F) Mixture of various colored clay minerals. (G) Laminated greenish clay. Note the collapse breccia texture. (H) Amorphous silica lump. Red stars indicate sample locations.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 10.

    Figure 10.Vertical geochemical variations for Test Trench in Tinanggea area. (A) Test Trench-1, (B) Test Trench-2.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 11.

    Figure 11.Selected photographs for pit survey of nickel laterite mine in South Palangga area in the southern part of 'Southeast-Arm' of Sulawesi. (A) Panoramic photograph for the studied pit. Note the very thick overburden above the nickel laterite deposits. (B) Bivalvia fossil discovered in Neogene mudstone (overburden). (C) Garnierite veins in saprolite orebody. (D) Amorphous garnierite fragments taken from garnierite veins. (E) Residual texture. Note the matrix of greenish serpentine.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 12.

    Figure 12.Photomicrographs of the nickel laterite deposits in South Palangga area. (A, B) Bedrock. (C, D) Saprolite zone. (E, F) Limonite zone. (A), (C) and (E) were taken under plane polarized light. (B), (D) and (F) were taken under crossed polarized light. op: opaque mineral, Im: ilmenite, Srp: serpentine, Opx: orthopyroxene, Ol: olivine, Spl: spinel.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 13.

    Figure 13.XRD patterns of bedrock, saprolite (SP-01 to SP-06), and limonite (LM-01) samples from South Palangga area showing their mineral components. Srp: serpentine, En: enstatite, Sm: smectite, Gt: goethite, Chl: chlorite, Tlc: talc, Tr: tremolite, Mag: magnetite, Cal: calcite, Hem: hematite, Kln: kaolinite.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 14.

    Figure 14.Representative drilling result in Ampana area in the northern part of 'East-Arm' of Sulawesi. (A) Drill core box showing laterite profile zones and (B) average chemical composition of core samples every 2m interval by XRF.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 15.

    Figure 15.(A) Nickel grade distribution map from drilling results for nickel laterite deposits in Ampana area. The nickel grade was calculated from average of chemical compositions by XRF data for each drill holes. GPS coordinate is based on WGS84 (datum) and UTM zone 5 (grid). (B) Representative cross section for the nickel laterite deposits. Its location is shown in (A). The laterite profile zones were interpreted from drilling results. Note ‘mirroring’ shape of nickel laterite deposits. Be cautious with the two different vertical scales for topography and drilling data.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Fig 16.

    Figure 16.Vertical geochemical variations for nickel laterite deposits in Ampana area.
    Economic and Environmental Geology 2023; 56: 343-363https://doi.org/10.9719/EEG.2023.56.3.343

    Table 1 . Chemical composition for nickel laterite deposits in Morombo area in the northeast part of 'Southeast-Arm' of Sulawesi.

    SampleZoneDepthSiO2TiO2Al2O3Fe2O3MnOCaOMgOK2ONa2OP2O5NiCoCr2O3LOITotal
    mwt.%
    SL-1-1SP141.630.021.4412.880.170.9340.19<0.01<0.01<0.010.420.010.721.3399.74
    SL-1-2SP440.490.011.7313.240.181.5240.08<0.01<0.01<0.010.440.010.701.3699.75
    SL-1-3SP833.810.032.8230.780.420.6020.16<0.01<0.01<0.011.330.041.957.5699.52
    SL-1-4SP1141.340.043.3422.280.310.5119.24<0.01<0.01<0.012.060.031.099.0599.33
    SL-1-5SP1341.910.043.5022.850.330.3816.92<0.01<0.01<0.012.690.031.329.2099.20
    SL-1-6SP1640.270.033.4121.840.311.0922.95<0.01<0.01<0.011.810.031.206.4199.38
    SL-1-7SP2039.040.033.1821.490.281.2327.52<0.01<0.01<0.011.160.021.114.5199.58
    SL-2-1LM137.530.044.4627.680.392.0517.06<0.01<0.01<0.011.150.041.537.6099.53
    SL-2-2SP341.59<0.011.8612.420.171.3738.21<0.01<0.01<0.010.570.010.752.7999.74
    SL-2-3SP737.630.032.6121.870.321.0229.66<0.01<0.01<0.011.180.031.243.9499.55
    SL-2-4SP1145.400.055.1517.900.260.8723.38<0.01<0.01<0.011.010.021.204.3299.57
    SL-2-5SP1547.100.032.0225.960.380.7413.95<0.01<0.01<0.011.420.041.506.3299.48

    The samples were analyzed in the laboratory PT. Carsurin Kendari, in accordance with WD-XRF fusion method for elemental and gravimetric method for LOI. SL-1: Survey Line-1, SL-2: Survey Line-2, LM: Limonite, SP: Saprolite, LOI: Loss On Ignition..


    Table 2 . Chemical composition for nickel laterite deposits in Morowali area in the northeast part of 'Southeast-Arm' of Sulawesi.

    SampleSiO2TiO2Al2O3Fe2O3MnOCaOMgOK2ONa2OP2O5NiCoCr2O3LOITotal
    wt.%
    LM-015.360.056.2864.942.690.022.27<0.01<0.01<0.011.500.294.2011.899.50
    SP-0139.540.021.9412.960.1630.3329.82<0.010.03<0.012.240.020.7011.699.40
    SP-0241.390.010.8010.060.130.4931.85<0.010.03<0.012.120.010.519.799.20
    SP-0341.210.010.9810.740.1260.7730.80<0.010.03<0.012.540.010.5811.399.30
    SP-0442.140.021.009.760.1310.8734.35<0.010.02<0.011.280.010.509.599.70
    SP-0541.85<0.010.768.720.1140.5133.51<0.010.03<0.012.020.010.474.899.60
    SP-0642.360.021.0410.510.1341.0532.25<0.010.03<0.010.40<0.010.598.799.90

    The samples were analyzed in the laboratory PT. Intertek Jakarta, in accordance with WD-XRF fusion method for elemental and gravimetric method for LOI. LM: Limonite, SP: Saprolite..


    Table 3 . Chemical composition for nickel laterite deposits in Tinanggea area in the southern part of 'Southeast-Arm' of Sulawesi.

    SampleZoneDepthSiO2TiO2Al2O3Fe2O3MnOCaOMgOK2ONa2OP2O5NiCoCr2O3LOITotal
    mwt.%
    TT1-1YL156.260.466.8625.880.390.180.810.440.140.040.640.060.996.3599.53
    TT1-2YL249.010.033.1427.960.570.655.190.040.03<0.012.190.091.309.3099.53
    TT1-3YL354.980.032.9823.270.760.415.810.070.04<0.011.650.061.038.4599.55
    TT1-4TZ468.250.021.3214.060.270.158.21<0.010.02<0.010.580.020.576.0599.51
    TT1-5TZ560.14<0.011.2513.610.120.6414.85<0.010.01<0.010.400.010.727.7899.52
    TT1-6TZ670.17<0.010.8610.080.080.1210.31<0.010.01<0.010.59<0.010.636.6599.50
    TT1-7TZ766.12<0.010.7012.280.150.1012.26<0.010.02<0.010.390.010.537.0199.56
    TT2-1RL113.160.118.0562.200.380.020.680.060.030.061.030.092.4910.9599.56
    TT2-2YL247.180.033.9326.580.960.746.540.010.02<0.012.950.121.249.2299.55
    TT2-3YL350.330.022.7428.870.330.455.84<0.010.02<0.011.470.041.487.9499.55
    TT2-4YL447.900.032.7735.440.470.401.99<0.010.02<0.010.980.061.647.7799.52
    TT2-5TZ573.600.021.9014.810.130.302.31<0.010.02<0.010.760.020.844.8499.56
    TT2-6TZ670.810.011.7315.440.190.283.20<0.010.02<0.010.790.031.046.0199.55
    TT2-7TZ774.54<0.011.5915.410.150.171.23<0.010.02<0.010.450.020.935.0299.52

    The samples were analyzed in the laboratory PT. Carsurin Kendari, in accordance with WD-XRF fusion method for elemental and gravimetric method for LOI. TT1: Test Trench-1, TT2: Test Trench-2, RL: Red Laterite, YL: Yellow Laterite, TZ: Transition Zone, LOI: Loss On Ignition..


    Table 4 . Chemical composition for nickel laterite deposits in South Palangga area in the southern part of 'Southeast-Arm' of Sulawesi.

    SampleSiO2TiO2Al2O3Fe2O3MnOCaOMgOK2ONa2OP2O5NiCoCr2O3LOITotal
    wt.%
    SP-0136.410.042.5417.060.280.4728.24<0.01<0.010.021.870.010.7111.9199.56
    SP-0232.690.021.1721.781.950.5525.24<0.01<0.010.011.86<0.010.5113.0698.84
    SP-0332.600.011.3426.470.270.3223.48<0.01<0.010.012.490.080.5011.3398.90
    SP-0439.410.021.1712.740.090.0832.37<0.01<0.010.011.170.030.5112.1599.75
    SP-0538.440.010.689.880.151.8233.78<0.01<0.010.010.770.010.4013.7299.67
    SP-0634.120.042.1420.110.840.2826.73<0.01<0.010.021.61<0.010.9812.8599.72
    LM-018.070.106.0972.531.050.183.020.02<0.010.031.560.132.664.2199.65

    The samples were analyzed in the laboratory PT. Carsurin Kendari, in accordance with WD-XRF fusion method for elemental and gravimetric method for LOI. LM: Limonite, SP: Saprolite, LOI: Loss On Ignition..


    Table 5 . Summary of chemical composition of mineralized drill holes (above 1% in average Ni grade) for nickel laterite deposits in Ampana area in the northern part of 'East-Arm' of Sulawesi.

    Zonenwt.%SiO2TiO2AI2O3Fe2O3MnOCaOMgONiCoCr2O3MCThickness (m)
    Total446Average31.070.167.5933.500.490.6112.951.190.051.4927.406.70
    Min4.790.010.285.310.040.030.980.030.000.050.002.00
    Max53.750.6820.4666.822.8611.3336.522.250.156.2641.5020.00
    Limonite171Average18.430.2510.7449.010.700.214.341.220.082.2329.703.60
    Min4.790.033.0324.680.110.030.980.420.030.580.001.00≤
    Max42.520.6820.4666.822.861.8111.592.130.156.2641.0010.00
    Saprolite245Average37.890.126.0425.470.380.7916.891.280.041.1127.703.60
    Min12.070.010.285.310.040.065.190.190.000.050.001.00≤
    Max51.370.5319.2054.691.927.8934.132.250.093.1041.5017.00
    Saprock/Bedrock30Average47.430.042.2910.660.141.4629.930.220.010.4112.00-
    Min41.970.011.045.840.080.1124.150.030.000.273.70-
    Max53.750.105.7815.520.2611.3336.520.530.020.5022.70-

    The samples were analyzed in the laboratory PT. Sucofindo Palu, in accordance with WD-XRF fusion method for elemental and gravimetric method for Moisture content (MC)..


    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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