In recent years, mineral resources near the surface are becoming scarce, causing focused mineral exploration on concealed deposits in covered terrains. In northern China, covered terrains are widespread and conceal bedrock sequences and mineralization. These represent geochemical challenges for mineral exploration in China. As a deep-penetrating geochemical technology that can reflect the information of deep anomalies, the fine-grained soil prospecting method has achieved ideal test results in arid Gobi Desert covered terrain, semi-arid grassland covered terrain, and alluvium soil covered terrain of northern China. The anomaly range indicated by the fine-grained soil prospecting method is very good with the known ore body location. The corresponding relationship can effectively indicate deep ore bodies and delineate anomalies in unknown areas. Overall, the fine-grained soil prospecting method can be applied to geochemical prospecting and exploration in covered terrains.

In recent decades, the human demand for mineral resources has increased dramatically, and the mining of shallow deposits has basically been completed. The prospecting direction has turned to concealed deposits. For this reason, various penetrating geochemical methods have been developed to find concealed minerals and a series of geochemical exploration techniques have been proposed. At the same time, the use of the geochemical gene as a new technique presented in recent years is feasible in discussing component classification and provenance tracing. In this study, we applied these methods for mineral exploration in the Jiaojia gold deposit in Shandong Province, China. The results show that a large number of ore-forming element particles can be observed in ores, fault muds, and soils; compared with Chinese soil, Au has higher enrichment coefficients; according to the LG03 lithogene, the ores belong to a neutral composition, and the fault muds and soils belong to an acidic composition. Based on the above results, it can be found that the ore-forming elements in the Jiaojia gold deposit have migrated. Although this migration cannot change the original lithology, it can provide theoretical support for the fine-grained soil-prospecting method.

Geogas-carried metal prospecting, an integral part of deep-penetrating geochemistry, is potentially effective in the geochemical exploration of concealed ore deposits. However, its principles and applicability remain controversial. This study summarizes and discusses the progress in geogas-carried metal prospecting in China. The method comprises three constituents: geogas, nanoparticles, and their vertical transportation. Researchers have failed to determine the exact contributions of different sources of geogas. Studies on Pb isotopes, rare earth element patterns of geogas, the comparisons between metals in soil, geogas, and ore geochemistry, and characteristics of nanoscale metals in earthgas (NAMEG), confirmed the relationship between NAMEG and concealed ore deposits. A statistical analysis of field experiments and applications showed that geogas-carried metal prospecting is applicable for the geochemical exploration of magmatic and hydrothermal Cu, Au, Zn, Pb, U, Sn, and Ag deposits and is suitable for most geochemical landscapes except deserts and cold swamps. Finally, genetic models of NAMEG anomalies were constructed. High-permeability migration channels are critical in the formation of NAMEG anomalies over concealed ore deposits. Future work entails applying geogas-carried metal prospecting to certain types of ore deposits and geochemical landscapes and studying NAMEG to provide quantitative information for targeting concealed ore deposits.

Antimony (Sb) is widely utilized in modern industries and classified as a critical mineral worldwide. China possesses the most abundant Sb mineral resources globally, with over 70% of proven reserves concentrated in southern China. However, due to excessive exploitation, the lifespan of Sb reserves is less than ten years. Therefore, the knowledge of Sb needs to be urgently strengthened. Here, the effectiveness of the geochemical block method to delineate the prospective areas of Sb deposits and determine the potential resource of Sb was studied, with geochemical data covering 2.3 million km² across southern China. The statistical results showed that the median concentration of Sb in stream sediments (1.05 ppm) in southern China was 1.5 times that of whole China, indicating a significantly elevated background level of Sb in southern China. By setting the threshold value at 2.98 ppm, a total of nine distinct geochemical blocks were delineated. Remarkably, 85% and 76% of the large and medium Sb deposits were located within these geochemical blocks, respectively. Taking the block containing the Xikuangshan giant Sb deposit in Hunan Province as the model, the metallogenic coefficient of Sb is calculated to be 0.32%. The total potential Sb resources in southern China within a depth of 1000 m are estimated to be 21.939 million tons, which are primarily concentrated in the provinces of Hunan, Guangxi, Yunnan, and Guizhou. When the threshold value is set at 4.19 ppm, the predicted potential resources of Sb are 21.45 million tons in twelve blocks, which closely approximate 21.939 million tons. The estimated Sb resource in this study significantly surpasses the proven reserves. The periphery and deep areas of known Sb deposits still hold promising prospects for exploration. This study highlighted the effectiveness of employing the geochemical block method to estimate the potential resources of Sb and determined the ore-prospecting direction of Sb deposits. However, it is important to acknowledge and address the overestimation of predicted resources resulting from the high geological background.

Aqueous complexation has long been considered the only viable means of transporting gold to depositional sites in hydrothermal ore-forming systems. Here, we present direct evidence supporting an alternative hypothesis, namely, the transport of gold as colloidal particles. We observed nano-scale gold particles adsorbed on halloysite and micro-scale gold particles in altered rocks by TEM and SEM in the Shanggong orogenic gold deposit. Based on this evidence, we propose a feasible model for the origin of microscopic gold particles in alteration zones. In the early stage of ore-forming fluid, gold may migrate in the form of collaurum, which is maintained by supercritical CO₂ and colloidal silica. Low salinity and high pressure are conducive to the stable migration of colloidal gold. When the physicochemical conditions change, some collaurum is precipitated and adsorbed by the clay minerals produced by hydrothermal alteration, and some collaurum undergoes growth and evolves into micro-submicrometer-sized gold particles. This study highlighted the significance of collaurum in the formation of orogenic gold deposits.