The Intex laterite deposit in Mindoro, Philippines is derived from the weathering of the ultramafic rocks under a tropical climate. This study investigates the several types of serpentines and the effect of the degree of chemical weathering of ultramafic rocks and laterites on the enrichment of Ni in the deposit. The five types of serpentines are differentiated based on their textural features and Raman spectral data. Type I, type II, type III, and type IV serpentines contain a low amount of NiO (average 0.15 wt%), and their formation is linked to the previous exhumation of the ultramafic body. Conversely, type V serpentines show the highest NiO contents (average 1.42 wt%) and have the composition of serpentine-like garnierites, indicating a supergene origin. In the limonite horizon, goethite is the main ore mineral and shows high NiO contents of up to 1.68 wt%, whereas the Mn-oxyhydroxides (i.e., asbolane and lithiophorite–asbolane intermediate) display substantial amounts of CoO (up to 11.3 wt%) and NiO (up to 15.6 wt%). The Ultramafic Index of Alteration (UMIA) and Index of Lateritization (IOL) are used to characterize the different stages of weathering of rocks and laterites. The calculated index values correspond to a less advanced stage of weathering of the Intex laterites compared with the Berong laterites. The Berong deposit is a Ni-Co laterite deposit in the Philippines, which is formed from the weathering of the serpentinized peridotite. The less extreme degree of weathering of the Intex laterites indicates less advanced leaching, and thereby the re-distribution of Ni, Si, and Mg from the limonite towards the saprolite horizon may have resulted in the poor precipitation of talc-like (kerolite-pimelite) and sepiolite-like (sepiolite-falcondoite) phases in the studied saprolite horizon. Nickel in the Intex deposit has undergone supergene enrichment similar to other humid tropical laterite deposits.

中文翻译：

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菲律宾民都洛Intex红土矿床中的镍钴矿化

菲律宾Mindoro的Intex红土矿床来自热带气候下超镁铁质岩石的风化作用。本研究调查了蛇纹石的几种类型，以及超镁铁质岩石和红土的化学风化程度对矿床中镍富集的影响。蛇纹石的五种类型根据其质地特征和拉曼光谱数据进行区分。I型，II型，III型和IV型蛇纹石含有少量的NiO（平均0.15 wt％），它们的形成与超镁铁矿体的先前发掘有关。相反，V型蛇纹石显示出最高的NiO含量（平均1.42 wt％），并具有蛇纹石状的针铁矿组成，表明是超基因起源。在褐铁矿层，针铁矿是主要的矿石矿物，其NiO含量高达1.68 wt％，而Mn-羟基氢氧化物（即，阿斯波烷和硫代磷灰石– Asbolane中间体）显示出大量的CoO（至多11.3 wt％）和NiO（至多15.6重量％）。超基性变指数（UMIA）和红化指数（IOL）用于表征岩石和红土风化的不同阶段。与Berong红土带相比，计算得出的指数值对应于Intex红土带的风化程度较低的阶段。Berong矿床是菲律宾的Ni-Co红土矿床，是由蛇纹化橄榄岩的风化形成的。Intex红土的风化程度越小，表明浸出越少，因此Ni，Si，从褐铁矿到腐泥土层的镁可能导致滑石状（滑石-黄铁矿）相和海泡石状（海泡石-方铁矿）相的降水较差。与其他潮湿的热带红土矿床相似，Intex矿床中的镍经历了超基因富集。