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"Daerah penelitian secara administratif berada di daerah Ganda-Ganda, KecamatanPetasia, Kabupaten Morowali Utara, Provinsi Sulawesi Tengah. Pelapukan batuanultramafik menghasilkan endapan laterit dengan karakteristik yang berbeda disetiapdaerah. Penelitian ini bertujuan untuk mengetahui karakteristik mineralogi dan geokimiaendapan nikel laterit dan batuan dasar, serta derajat laterisasi dan distribusinya padadaerah penelitian. Data yang digunakan merupakan data lapangan dari 6 profil lateritberupa 39 sampel batuan dan tanah, serta data assay dari analisis XRF (X-RayFluorescence) dan XRD (X-Ray Diffraction). Profil laterit pada daerah penelitian terdiridari limonit dengan kadar Ni 0,2 – 0,47%, serta saprolit 0,23 – 0,89% (termasuk sampelbedrock). Sampel bedrock yang merupakan bongkah batuan disekitar lapisan saprolitsecara mineralogi dianggap mewakili batuan dasar di bawah permukaan, memiliki kadarNi 0,56 – 0,89% dan diinterpretasikan merupakan rocky saprolite. Nikel pada limonitsecara dominan berasosiasi dengan mineral goetit dan gibsit, sementara pada saprolitberasosiasi dengan mineral serpentin (lizardit dan antigorit), talk, olivin (forsterit danfayalit), dan piroksen (enstatit). Derajat laterisasi pada daerah penelitian menunjukkanlimonit mengalami moderate – strongly lateritized, saprolit kaolinitized – stronglylaterized dan Index of laterization (IOL) berkorelasi positif dengan hubungan korelasikuat terhadap Fe pada limonit, saprolit, dan bedrock, sementara berkorelasi negatifterhadap Ni dengan hubungan lemah pada sampel bedrock.

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The research area is administratively located in Ganda-Ganda, Petasia District,

North Morowali Regency, Central Sulawesi Province. Weathering of ultramafic rocks

produces laterite deposits with different characteristics in each area. This study aims to

determine the mineralogical and geochemical characteristics of nickel laterite deposits

and bedrock, as well as the degree of laterization and its distribution in the research area.

The data used include field data from 6 laterite profiles consisting of 39 rock and soil

samples, as well as assay data from XRF (X-Ray Fluorescence) and XRD (X-Ray

Diffraction) analyses. The laterite profiles in the study area consist of limonite with Ni

content of 0.2 – 0.47%, and saprolite with Ni content of 0.23 – 0.89% (including bedrock

samples). The bedrock samples, which are rock fragments around the saprolite layer, are

mineralogically considered to represent the bedrock beneath the surface, with Ni content

of 0.56 – 0.89% and are interpreted as rocky saprolite. Nickel in limonite is predominantly

associated with the minerals goethite and gibbsite, while in saprolite it is associated with

serpentine minerals (lizardite and antigorite), talc, olivine (forsterite and fayalite), and

pyroxene (enstatite). The degree of laterization in the study area shows that limonite is

moderately to strongly lateritized, saprolite is kaolinitized to strongly laterized, and the

Index of Laterization (IOL) positively correlates with Fe in limonite, saprolite, and

bedrock, while it negatively correlates with Ni with a weak correlation in bedrock

samples."

"Daerah Ganda-Ganda, Morowali Utara merupakan salah satu daerah penghasil bijih nikel di Indonesia dari endapan laterit. Endapan laterit tersebut dihasilkan dari pelapukan batuan ultramafik (batuan asal). Pada area penelitian terdapat pada Komplek Ultramafik dari Jalur Ofiolit Sulawesi. Penelitian ini bertujuan untuk mengetahui komposisi endapan laterit, karakteristik batuan ultramafik, dan asosiasinya terhadap tektonik dari sampel batuan asal daerah penelitian. Metode yang digunakan yakni analisis petrografi, X-Ray diffraction (XRD), dan energy dispersive X-Ray fluorescence (EDXRF). Profil terdiri atas limonit dan saprolit hingga rocky saprolite. Komposisi mineral profil limonit didominasi goetit dan gibbsit. Saprolit didominasi antigorit, talk, lizardit, dan nakrit. Batuan asal didominasi mineral silikat. Jenis batuan ultramafiknya meliputi lherzolit terserpentinisasi, harzburgit terserpentinisasi, olivin websterit terserpentinisasi, dan serpentinit. Secara geokimia semua batuan ultramafik berkomposisi lherzolit. Semua batuan hadir mikrotekstur mesh. Banyak mineral olivin dan piroksen di batuan asal telah terubah menjadi mineral serpentin. Mikrotekstur serpentinit mencangkup tekstur mesh pada lizardit, tekstur relict pada olivin, tekstur veinlet mineral krisotil, dan tekstur decussate mineral antigorit. Komposisi batuan asal dominan tersusun atas mineral olivin, lizardit, dan piroksen. Batuan ultramafik daerah penelitian berasosiasi dengan tektonik supra-subduction zone (SSZ) yang dominan hingga mid-oceanic ridge basalt (MORB) dengan seri magma tholeiite.

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The Ganda-Ganda area, North Morowali is one of the nickel ore producing areas in Indonesia from laterite deposits. Laterite deposits are produced from the weathering of ultramafic rocks (source rocks). The research area is in the Ultramafic Complex of the Sulawesi Ophiolite Belt. This research aims to determine the composition of laterite deposits, the characteristics of ultramafic rocks, and their association with tectonics from the source rock samples from the research area. The methods used are petrographic analysis, X-ray diffraction (XRD), and energy-dispersive X-ray fluorescence (EDXRF). The profile consists of limonite and saprolite to rocky saprolite. The mineral composition of the limonite profile is dominated by goethite and gibbsite. Saprolite is dominated by antigorite, talc, lizardite, and nacrite. The source rocks are dominated by silicate minerals. Ultramafic rock types include serpentinized lherzolite, serpentinized harzburgite, serpentinized olivine websterite, and serpentinite. Geochemically, all ultramafic rocks fall in the lherzolite composition. All rocks have mesh microtexture. Many of the olivine and pyroxene minerals of the source rock have been altered into serpentine minerals. Serpentinite microtextures include the mesh texture of lizardite, the relict texture of olivine, the veinlet texture of chrysotile, and the decussate texture antigorite. The dominant composition of the source rocks consists of olivine, lizardite and pyroxene minerals. Ultramafic rocks in the study area are dominantly associated with supra-subduction zone (SSZ) tectonics to mid-oceanic ridge basalt (MORB) with a tholeiite magma series."