http://journal.uir.ac.id/index.php/JGEET E-ISSN : 2541-5794 P-ISSN :2503-216X Journal of Geoscience, Engineering, Environment, and Technology Vol 5 No 2 2020 Jahidin et al./ JGEET Vol 5 No 2/2020 59 RESEARCH ARTICLE Analysis of Ultramafic Rocks Weathering Level in Konawe Regency, Southeast Sulawesi, Indonesia Using the Magnetic Susceptibility Parameter Jahidin1,*, LO. Ngkoimani2, LM. Iradat Salihin3, Hasria2, Erzam S. Hasan4, Irfan Ido5, Suryawan Asfar2 1Geophysics Engineering Department, Halu Oleo University, Kendari 93232, Indonesia. 2Geological Engineering Department, Halu Oleo University, Kendari 93232, Indonesia. 3Geographic Department, Halu Oleo University, Kendari 93232, Indonesia. 4Physics Department, Halu Oleo University, Kendari 93232, Indonesia. 5Mining Engineering Department, Halu Oleo University, , Kendari 93232, Indonesia. * Corresponding author : jahidin_geofisika@uho.ac.id Tel.:+62-81-388-3535-48; fax: - Received: Dec 13, 2019. ; Accepted:May 20, 2020. DOI 10.25299/jgeet.2020.5.2.4247 Abstract The Konawe region is part of the Sulawesi Southeast Arm ophiolite belt where ultramafic rocks are exposed in the form of dunite and peridotite. The formation of nickel deposits is closely related to the weathering process of ultramafic rocks as a source rock. Ultramafic rocks exposed to the surface will experience weathering which is influenced by many factors, including in the form of climate change, topography, and existing geological structures. The weathering process in the source rock can influence variations in chemical elements and magnetic properties in laterite soil profiles. For example, the chemical weathering might affect magnetic mineralogy and the physical weathering could affect granulometry as well as the quantity of magnetic minerals in the soil. Condition of weathering of ultramafic rocks (initial, moderate and advanced) can affect nickel content in laterite sediments. The weathering profile study of serpentine mineral is an indication of the lateralization process that occurs in ultramafic rocks and is carried out through petrographic analysis of thin cuts and polish cuts. Determination of weathering level like this is based on the level of weathering of the mineral serpentine. In this study, the determination of the weathering level of ultramafic rocks (initial, moderate, and continued) uses magnetic susceptibility parameter. A total of 232 ultramafic rock core samples obtained from 34 hand samples were taken from different places and weathered levels were analyzed. The results of the research have shown that the magnetic susceptibility of ultramafic rocks i n the study area varies, from 580 x 10-6 SI to 4.724 x 10-6 SI. Based on the value of magnetic susceptibility, magnetic minerals contained in ultramafic rock samples are hematite and geotite minerals. This means that the weathering level of ultramafic rock samples is the continued weathering level. The level of continued weathering that occurs in ultramafic rocks in the study area produces nickel laterite deposits with a nickel content of 1.65 - 2.40% in the saprolite zone, 0.42% in the saprock zone, and 0.20 - 0.51% in the basic rock zone (bedrock). Keywords: Ultramafic rock, weathering level, magnetic susceptibility, Konawe Regency. 1. Introduction 1.1 Background of Research The Konawe area is part of the Sulawesi Southeast Arm ophiolite belt. In this section, ultramafic rocks are formed in the form of dunite and peridotite (Surono, 2010). The formation of nickel deposits is closely related to the weathering process of ultramafic rocks as a source rock. Ultramafic rocks exposed to the surface will experience weathering which is influenced by many factors, including in the form of climate change, topography, and existing geological structures. The weathering process in the source rock can influence variations in chemical elements (Maher and Thompsons, 1999) and magnetic properties in laterite soil profiles (Evans and Heller, 2003; Yulianto et al., 2003). For example, the chemical weathering might affect magnetic mineralogy and the physical weathering couldaffect granulometry as well as the quantity of magnetic minerals in the soil. The process of soil formation is divided into several zones with varying thickness and mineral element content (Petrovsky and Ellwood, 1999), for example in laterite soil deposits (Sundari, 2012). Laterite soils or commonly called laterite or red soil isa type of infertile soil that is fertile and rich in nutrient-rich soil, but it is lost because it is dissolved by high rainfall. This type of soil has a low cation exchange capacity (which causes the metabolic process of plants to be disrupted (Sudarningsih, 2008). According to Sembiring (2008) the land of ex-laterite nickel mining actually shows the condition of the soil that has damaged structure and compaction so that it has a negative effect on the water system and aeration which can directly affect the function and development of roots. This causes the plants to grow normally, dwarf, wither, and die. The deterioration of the soil structure also affects the soil that is unable to store and absorb water during the rainy season resulting in soil erosion. Conversely, in the dry season the soil becomes hard http://journal.uir.ac.id/index.php/JGEET 60 Jahidin et al./ JGEET Vol 5 No 2/2020 and dense, so the soil becomes difficult to cultivate. Therefore, efforts are needed to increase soil fertility. Exploration of laterite nickel deposits is thought to be related to weathering of ultramafic rocks in the formation of laterite nickel deposits and the presence of erosion material spread over the surface. In humid tropical climatic conditions, ultramafic rocks decay very quickly and produce ore residues containing nickel, chromium, or iron (Sudarningsih, 2008). The weathering profile study of serpentine mineral is an indication of the lateralization process that occurs in ultramafic rocks and is carried out through petrographic analysis and polish cuts (Boldt, 1967). Determination of weathering levels like this is based on the level of weathering of the mineral serpentine. In this study, the determination of the weathering level of ultramafic rocks (early, moderate, and continued) uses magnetic susceptibility parameter. This is new and is expected to be an inexpensive and environmentally friendly alternative method for assessing weathering of ultramafic rocks and their relationship to nickel content. An illustration of the relationship of weathering levels of ultramafic rocks with nickel content can be used to support the exploration of the presence of laterite nickel. 1.2 Basic Theory According to regional geology, Sulawesi is located at the confluence of 3 large plates, which causes very complex tectonic conditions, where a collection of rocks from the archipelago, ophiolite, and chunks of microcontinent are carried along with subduction, collision and other tectonic processes (Surono,2010). For the Southeast Sulawesi region which is in the East Sulawesi Ophiolite Lane group, the rocks consist of mafic and ultramafic rocks accompanied by pelagic and melange sedimentary rocks in several places. Ultramafic rocks are dominant in the Southeastern Arm, but the mafic rocks are dominant further north, especially along the North coast of the Southeast Arm of Sulawesi (Fig. 1). The weathering rock is a process of physical disintegration and chemical decomposition of rock material that is on the surface or near the surface of the earth (Parker, 1997 in Waheed, 2002). Ultramafic rocks that undergo chemical weathering will change the composition of the mineral, as illustrated in Table 1. Fig. 1. Map of the Geology of the Southeast Arm of Sulawesi (Surono, 2010). Table 1. Mineral content at weathering level (Mitchell & Soga, 2005) Weathering Level Mineral Content Early weathering level Gypsum (also halite, sodium nitrat) Calcite (also dolomite apatite) Olivine-hornblende (also pyroxenes) Biotite (also glauconite, nontronite) Albite (also anorthite, microcline, orthoclase) Moderate weathering level Quartz Muscovite (also illite) Layer silicate (including vermiculite, expanded hydrous mica) Montmorillonite Continued weathering level Kaolinite Gibbsite Hematite (also goethite, limonite) Anatase (also rutile, zircon) Jahidin et al./ JGEET Vol 5 No 2/2020 61 2. Research Method Samples in the form of ultramafic rocks and soil analyzed in this study were taken at Pondidaha District and Puriala District Konawe Regency. The samples were taken at the nickel mining site, rock mining, and post nickel mining. For rock samples, they are taken in the form of hand samples and made in the core for magnetic susceptibility measurement purposes and made in powder form for the measurement of mineral / elemental content. Measurement of the magnetic susceptibility of ultramafic and soil rock was carried out on 232 ultramafic rock core samples obtained from 34 hand samples and 20 soil samples taken around ultramafic rocks. Magnetic susceptibility values for each rock and soil sample site were measured using the MS2B susceptibilitymeter. Measurement of mineral content/sample elements was performed using X-Ray Difraction and X-Ray Fluorescence. 3. Results and Discussion 3.1 Magnetic Susceptibility of Samples Magnetic susceptibility is a function of the concentration, grain size and type of magnetic minerals. Variable magnetic susceptibility values indicate the concentration of magnetic minerals, grain size, and types of magnetic minerals that vary (Jahidin et al., 2019). The greater the value of magnetic susceptibility means the more concentration of magnetic minerals. High magnetic susceptibility also shows that magnetic mineral typesare dominated by ferrimagnetic and ferromagnetic magnetic minerals, magnetic susceptibility in the medium category is dominated by paramagnetic and antiferromagnetic magnetic minerals, whereas magnetic susceptibility is very low (negative) including non-magnetic (diamagnetic) minerals. The magnetic susceptibility values for each rock and soil sample site measured using the MS2B susceptibility instrument can be seen in Table 2. Table 2. The magnetic susceptibility value of the samples Sample Type Site Name Number of Hand Samples Number of Core Samples Location Magnetic Susceptibility Value (x 10-6 SI) Ultramafic rock P1 2 23 Rock mining (Puriala District) 960 - 2.128 P2 2 16 Rock mining (Puriala District) 690 - 1364 P3 2 26 Rock mining (Puriala District) 1.610 - 2.860 ST2 2 9 Rock mining (Puriala District) 1.218 - 4.724 ST3 1 2 Rock mining (Puriala District) 3.700 - 4.364 D1 3 16 Post nickel mining(Pondidaha district) 679 - 1.439 D2 4 32 Nickel mining(Pondidaha district) 640 - 1543 D3 9 70 Post nickel mining(Pondidaha district) 580 - 1460 ST1 2 6 Nickel mining(Pondidaha district) 666 - 814 ST2 2 9 Post nickel mining(Pondidaha district) 586 - 901 ST3 3 10 Rock mining(Pondidaha district) 992 - 1.434 ST5 2 8 Nickel mining(Pondidaha district) 894 - 1.603 Soil ST1 1 3 Nickel mining(Pondidaha district) 37,9 - 40,3 ST2 1 2 Post nickel mining(Pondidaha district) 334,6 -381,6 ST3 1 2 Rock mining(Pondidaha district) 71,8 - 119,8 ST5 3 7 Nickel mining(Pondidaha district) 91,4 - 156,6 ST2 1 2 Rock mining (Puriala District) 959,5 - 991,3 ST3 1 2 Rock mining (Puriala District) 269,2 - 285,9 Based on the Table 2, it can be seen that the magnetic susceptibility value in ultramafic rock samples and soil samples in the study area varies. Ultramafic rock samples have magnetic susceptibility values ranging from580 x 10-6 SI to 4,724 x 10-6 SI and soilsamples have magnetic susceptibility values of 37.9 x 10-8 m3/kg to 991.3 x 10-8 m3/kg. Ultrabasic rock samples such as P3, ST2, and ST3 sites in Puriala District show a greater magnetic susceptibility than other sites. The magnitude of the magnetic susceptibility value indicates that the concentration of magnetic minerals in the sample is higher and is suspected to have a different type of magnetic mineral than the others. In soil samples taken from around the area of the presence of ultramafic rocks, the magnetic susceptibility value per unit of mass indicates that the soil samples originated from weathering of host rock (ultramafic rocks). Based on the value of magnetic susceptibility and field observations, it is suspected that soil samples contain the same magnetic minerals as ultramafic rocks. From the results of the measurement of magnetic susceptibility in some ultramafic rock samples that produce two or more core samples from hand sample drilling, it is found that the magnetic susceptibility values for the cores above tend to be greater than the cores below. The above cores are samples taken from rock drilling in the uppermost structure, while the next cores are in the lower structure. The existence of the upper core has a high magnetic susceptibility compared to the bottom core due to weathering ultramafic rock always starts at the top of the structure towards the bottom structure. This allows a greater concentration of magnetic minerals in the upper core than the bottom core. The presence of magnetic susceptibility values of the lower core is higher than the upper core may be caused by the structure in the form of fractures at the bottom so that it will facilitate the entry of water and means the weathering process will be more intensive. As a result, the concentration of magnetic minerals at the bottom becomes greater and the value of magnetic susceptibility becomes higher. Next, the magnetic 62 Jahidin et al./ JGEET Vol 5 No 2/2020 136 144 145,8 0 0 0 111,6 99 106,3 0 20 40 60 80 100 120 140 160 P1.2.1 P1.2.2 P1.4.1 P1.4.2 P1.8.1 P1.8.2 M a g n e ti c S u sc e p ti b il it y ( x 1 0 -5 S I) Sample Code Core 1 Core 2 79,5 92,4 105,5 107,1 92,7 136,4 0 0 0 0 0 0 69 94 98,4 106 82,2 118 0 20 40 60 80 100 120 140 160 P2.1.1 P2.1.2 P2.3.1 P2.3.2 P2.4.1 P2.4.2 P2.5.1 P2.5.2 P2.6.1 P2.6.2 P2.8.1 P2.8.2 M a g n e ti c S u sc e p ti b il it y ( x 1 0 -5 S I) Sample Code Core 1 Core 2 421 276 386,5 292,9 161 228,6 168 154,9 205 197,5 197 264,5 213 386,5 234 187,8 287 182,3 163,9 204 239 174,6 0 50 100 150 200 250 300 350 400 450 M a g n e ti c S u sc e p ti b il it y ( x 1 0 -5 S I) Sample Code Core 1 Core 2 susceptibility values for the cores at each site are shown in Fig.2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig.7, and Fig. 8. Fig. 2. Magnetic susceptibility values of upper core (core 1) and bottom core (core 2) ultramafic rock samples at Site P1 Puriala District Fig. 3 Magnetic susceptibility values of the upper core (core 1) and bottom core (core 2) ultramafic rock samples at Site P2 Puriala District Fig. 4 Magnetic susceptibility values of upper core (core 1) and bottom core (core 2) ultramafic rock samplesat Site P3 Puriala District Jahidin et al./ JGEET Vol 5 No 2/2020 63 160,5 68,9 72,8 151,3 111,2 67,9 71,7 89,5 0 50 100 150 200 D1.1.4 D1.2.1 D1.2.4 D1.3.3 M a g n e ti c S u sc e p ti b il it y ( x 1 0 -5 S I) Sample Code core 1 core 2 114,4 89,5 95,8 85,3 107,5 95 73,1 87,5 86,3 74,8 69,2 66 117,1 154,3 100,3 92,7 90,7 74,8 94,3 76,8 70,7 71,2 72,3 72,6 66,9 64 114,5 121,8 0 20 40 60 80 100 120 140 160 180 M a g n e ti c S u sc e p ti b il it y ( x 1 0 -5 S I) Sample Code core 1 core 2 89,1 80,6 80,2 89,2 72 97,6 87,5 66,7 74,7 79,5 81 70,7 148,6 91 103,4 81 75,5 124,4 96,8 141,6 108,5 141 100 128 59,5 0 0 0 0 87,5 76 72,2 73,2 68,5 92,6 73,2 65,1 72 77 81,5 70 90 65 76 84 67,5 85,5 99 102 106 111 112 120,5 58 0 20 40 60 80 100 120 140 160 D 3 .1 .1 D 3 .1 .2 D 3 .1 .3 D 3 .2 .1 D 3 .2 .3 D 3 .3 .1 D 3 .3 .4 D 3 .3 .7 D 3 .4 .2 D 3 .4 .3 D 3 .4 .4 D 3 .5 .2 D 3 .5 .3 D 3 .5 .4 D 3 .5 .5 D 3 .5 .6 D 3 .5 .7 D 3 .5 .8 D 3 .6 .2 D 3 .7 .3 D 3 .7 .5 D 3 .7 .7 D 3 .7 .9 D 3 .7 .1 0 D 3 .9 .4 M a g n e ti c S u sc e p ti b il it y ( x 1 0 -5 S I) Sample Code core 1 Fig. 5 Magnetic susceptibility values of upper core (core 1) and bottom core (core 2) ultramafic rock samples at Site D1 Pondidaha District Fig 6. Magnetic susceptibility values of the upper core (core 1) and bottom core (core 2) ultramafic rock samples at Site D2Pondidaha District Fig. 7 Magnetic susceptibility values of the upper core (core 1) and bottom core (core 2) ultramafic rock sample at Site D3 Pondidaha District 64 Jahidin et al./ JGEET Vol 5 No 2/2020 Fig 8. Magnetic susceptibility values of core 1, core 2, core 3, core 4, core 5 ultramafic rock samples at Site ST3, ST2, ST5, and ST1 Pondidaha District 3.2 Mineral Content of Samples The magnetic mineral content in the sample can be determined based on the magnetic susceptibility value. By referring to the classification of magnetic mineral types based on magnetic susceptibility prices according to Hunt et al. (1995), the magnetic mineral content of ultramafic and soil rock samples can be seen in Table 3. Table 3. Magnetic mineral content of ultramafic and soil rock samples Sample Type Site Name Area Magnetic Susceptibility Value (x 10-6 SI) Type of Magnetic Mineral Ultramafic rock P1 Puriala District 960 - 2.128 Hematite (αFe2O3) Geotite (FeOOH) P2 Puriala District 690 - 1364 Hematite (αFe2O3) Geotite (FeOOH) P3 Puriala District 1.610 - 2.860 Hematite (αFe2O3) Geotite (FeOOH) ST2 Puriala District 1.218 - 4.724 Hematite (αFe2O3) Geotite (FeOOH) ST3 Puriala District 3.700 - 4.364 Hematite (αFe2O3) Geotite (FeOOH) D1 Pondidaha District 679 - 1.439 Hematite (αFe2O3) D2 Pondidaha District 640 - 1543 Geotite (FeOOH) D3 Pondidaha District 580 - 1460 Hematite (αFe2O3) ST1 Pondidaha District 666 - 814 Geotite (FeOOH) ST2 Pondidaha District 586 - 901 Hematite (αFe2O3) ST3 Pondidaha District 992 - 1.434 Geotite (FeOOH) ST5 Pondidaha District 894 - 1.603 Hematite (αFe2O3) Soil ST1 Pondidaha District 37,9 - 40,3 Hematite (αFe2O3) ST2 Pondidaha District 334,6 -381,6 Hematite (αFe2O3) Ilmenite (FeTiO3) ST3 Pondidaha District 71,8 - 119,8 Hematite (αFe2O3) Ilmenite (FeTiO3) ST5 Pondidaha District 91,4 - 156,6 Hematite (αFe2O3) Ilmenite (FeTiO3) ST2 Puriala District 959,5 - 991,3 Ilmenite (FeTiO3) ST3 Puriala District 269,2 - 285,9 Hematite (αFe2O3) Ilmenite (FeTiO3) Jahidin et al./ JGEET Vol 5 No 2/2020 65 The presence of hematite and geotite magnetic minerals in the ultramafic rock samples was also confirmed by XRD (X-Ray Difraction) analysis. In addition to the magnetic minerals in the form of hematite and geotite, in the ultramafic rock samples there are other minerals in the form of olivine minerals, cristabolite, wuestite, calcite, and nickel. The presence of hematite and ilmenite magnetic minerals in soil samples is also confirmed by the results of the XRF (X-Ray Fluorescence) analysis. Based on the results of the XRF analysis, obtained elemental content in soil samples in the form of Fe and Ti as the forming elements of hematite and ilmenite minerals. 3.3 Weathering Level of Ultramafic Rock Samples To find out the level of weathering of ultramafic rocks in the study area, an analysis was made of the presence of magnetic minerals in rock samples based on the magnetic susceptibility of the sample. With reference to the mineral content in the rock weathering level as contained in Table 1, the presence of magnetic minerals in the form of hematite and geotite in the sample shows that the weathering level of ultramafic rocks in the study area is the continued weathering level. Overall, a description of the weathering level of rock samples by site and sub-district in the study area can be seen in the following Table 4. Table 4. Weathering level of ultramafic rock samples Site Name Area Type of Ultramafic Rock Magnetic Susceptibility Value (x 10-6 SI) Type of Magnetic Mineral Weathering Level P1 Puriala District Olivine websterite 960 - 2.128 Hematite (αFe2O3) Geotite (FeOOH) Continued P2 Puriala District Olivine websterite 690 - 1364 Hematite (αFe2O3) Geotite (FeOOH) Continued P3 Puriala District Lherzolite 1.610 - 2.860 Hematite (αFe2O3) Geotite (FeOOH) Continued ST2 Puriala District Lherzolite 1.218 - 4.724 Hematite (αFe2O3) Geotite (FeOOH) Continued ST3 Puriala District Lherzolite 3.700 - 4.364 Hematite (αFe2O3) Geotite (FeOOH) Continued D1 Pondidaha District Lherzolite 679 - 1.439 Hematite (αFe2O3) Continued D2 Pondidaha District Lherzolite 640 - 1543 Geotite (FeOOH) Continued D3 Pondidaha District Lherzolite 580 - 1460 Hematite (αFe2O3) Continued ST1 Pondidaha District Lherzolite 666 - 814 Geotite (FeOOH) Continued ST2 Pondidaha District Lherzolite 586 - 901 Hematite (αFe2O3) Continued ST3 Pondidaha District Lherzolite 992 - 1.434 Geotite (FeOOH) Continued ST5 Pondidaha District Lherzolite 894 - 1.603 Hematite (αFe2O3) Continued In the study area, determination of weathering levels of ultramafic rock samples and nickel content contained in laterite sediments was carried out on several samples representing different sites and sub-district areas. The analysis results of these samples are presented in Table 5. Table 5. Weathering level of ultramafic rocks and nickel content Weathering Level Name of Ultramafic Rock Sample Site Name of Soil Samples Area Nickel Content (%) Finding in Laterite Sedimentary Layer Continued ST2 ST2 Puriala District 2,34 Saprolite Continued ST3 ST3 Puriala District 2,40 Saprolite Continued ST1 ST1.1 Pondidaha District 2,37 Saprolite Continued ST2 ST2.1 Pondidaha District 2,40 Saprolite Continued ST3 ST3.1 Pondidaha District 0,42 Saprock Continued ST5 ST5.1 ST5.2 ST5.3 Pondidaha District 1,65 2,08 1,96 Saprolite Saprolite Saprolite Continued D2 on the core: D2.1.5.1 D2.1.5.2 D2.1.5.3 Pondidaha District 0,51 0,30 0,29 Bedrock Continued D3 on the core: D3.5.3.2 Pondidaha District 0,20 Bedrock 4. Conclusion Based on the finding in this study, some conclusions can be summarized, as the following : 1. The magnetic susceptibility value of ultramafic rocks in the study area varies from 580 x 10-6 SI to 4,724 x 10-6 SI. The magnetic susceptibility of ultramafic rock samples shows different values in the upper and lower cores where the magnetic upper core susceptibility values tend to be greater. This relates to the weathering process which always starts in the upper structure so that it allows greater concentrations of magnetic minerals. The difference in value indicates that the magnetic susceptibility parameter can explain the weathering conditions of ultramafic rocks. 2. The magnetic minerals present in the ultramafic rock samples are hematite and geotite minerals. In addition to these two magnetic minerals, there are other minerals in the form of olivine minerals, cristabolite, wuestite, calcite, and nickel. 3. Based on the value of magnetic susceptibility of ultramafic rock samples which shows the magnetic susceptibility of hematite and geotite minerals, the weathering level of ultramafic rock samples in the study 66 Jahidin et al./ JGEET Vol 5 No 2/2020 area includes continued weathering level (magnetic susceptibility value of samples is 580 x 10-6 SI to 4,724 x 10-6 SI). 4. The level of weathering of ultramafic rocks can affect nickel content in lateritic nickel sediments. The level of continued weathering that occurs in ultramafic rocks in the study area produces nickel laterite deposits with a nickel content of 1.65 - 2.40 % in the saprolite zone, 0.42 % in the saprock zone, and 0.20 - 0.51 % in the basic rock zone (bedrock). Acknowledgment This research was supported by University of Halu Oleo (UHO). We thank to LPPM UHO for helping in funding this research through the DIPA UHO fund in 2019. References Boldt, 1967. Laterit Deposites, Mc. Farlane Publish Dearing, J., 1999, Environmental Magnetic Susceptibility: Using the Bartington MS2 System. Chi Publishing, Keniloworth. Evans, A.M., 1993. Ore Geology and Industrial Minerals. Blackwell Scientific Publications, Oxford,390 pp. Hunt, C., Moskowit, B.M., Banerje, S.K., 1995, Magnetik Properties of Rock and Minerals. In T. J. Ahrens (Ed.), Handbook of Physical Contants, (Vol. 3, pp. 189-204), American Geophysical Union. Isaac, R.A. dan J.D. Kerber, 1971, Atomic absorption and flame photometry: Techniques and uses in soil, plant, and water analysis. In L.M. Walsh (ed), Instrumental methods for analysis of soils and plant tissue. Soil Sci. Soc. of Amer., Inc. Ma., Wisc. USA. Jahidin, Ngkoimani, L.O., Ilmawati, W.O.S., Iradat Salihin, L.M., Irawati, Usmardin, Al Firman, Harisma, and Okto, A., 2019, The magnetic susceptibility analyzes of Motonuno lake sediment in Muna Regency, Southeast Sulawesi, Indonesia, IOP Conf. Series: Earth and Environmental Science 311 (2019) 012037 IOP Publishing doi:10.1088/1755-1315/311/1/01. M.E. Evans and F. Heller, 2003, Environmental magnetism. Principles and applications of enviromagnetics. Academic Press, San Diego (311pp). Maher, B. and Thompsons, R., 1999, Quartenary climates, environments and magnetism, Cambridge university press, pp. 390. Mitchell, J.K. and K. Soga, 2005. Fundamental of Soil Behavior. 3rded. John Wiley & Sons, Inc. United States of America. 558p. Petrovsky E, Ellwood B B 1999 Magnetic monitoring of pollution of air, waters. In: Maher, B.A., Thompson, R. (Eds.), Quaternary Climates, Envand Magnetism, Cambridge University Press, Cambridge, pp. 279-322. Waheed, A., 2002, Nickel Laterite: A Short Course on The Chemistry, Mineralogy and Formation of Nickel Laterites, PT. INCO, Indonesia. Sembiring S. 2008. Sifat kimia dan fisik tanah pada areal bekas tambang bauksit di Pulau Bintan, Riau. Balai Penelitian Kehutanan Aek Nauli. Sumatera Utara. 5(2): 123-134. Sudarningsih dan Fahruddin, 2008. Penggunaan Metoda Difraksi Sinar X dalam Menganalisa Kandungan mineral pada Batuan Ultrabasa Kalimantan Selatan. Staf Pengajar Program Studi Fisika FMIPA, Universitas Lampung Mangkurat. Sundari, W., 2012, Analisis Data Eksplorasi Bijih Nikel Laterit Untuk Estimasi Cadangan Dan Perancangan Pit Pada PT. Timah Eksplomin Di Desa Baliara Kecamatan Kabaena Barat. Kabupaten Bombana Provinsi Sulawesi Tenggara. Prosiding Seminar Nasional Aplikasi Sains & Teknologi (SNAST) Periode III ISSN: 1979-911X, 3 November 2012: Yogyakarta. Surono, 2010, Geologi Lengan Tenggara Sulawesi. Bandung: Badan Geologi, Kementerian Energi dan Sumber Daya Mineral. Yulianto, A., Bijaksana, S., Loeskmanto, W., dan Kurnia, D., 2003, Produksi Hematit ( -Fe2O3) dari pasir besi: Pemanfaatan potensi alam sebagai bahan industri berbasis sifat kemagnetan, Jurnal Sains Materi Indonesia, 5 (1), 5154. © 2020 Journal of Geoscience, Engineering, Environment and Technology. All rights reserved. This is an open access article distributed under the terms of the CC BY-SA License (http://creativecommons.org/licenses/by- sa/4.0/). http://creativecommons.org/licenses/by-sa/4.0/ http://creativecommons.org/licenses/by-sa/4.0/ http://creativecommons.org/licenses/by-sa/4.0/