BACKGROUNDSufficient mineralogical research on clay-type lithium resources is an important prerequisite for lithium extraction and leaching. Numerous clay-type lithium resources have been discovered in both Yuxi City of Yunnan Province in China and the state of Nevada in the USA; however, existing research on their mineralogical characteristics is relatively insufficient.

OBJECTIVESTo explore the main chemical composition, phase composition, microscopic morphology, Li occurrence and other characteristics of clay-type lithium resource samples from Yuxi and Nevada and to provide theoretical support for the extraction and leaching of clay-type lithium resources in these two areas.

METHODSX-ray fluorescence spectroscopy, inductively coupled plasma emission spectroscopy, inductively coupled plasma mass spectrometry, powder crystal X-ray diffraction analysis, and scanning electron microscopy were used to analyze the mineral and chemical differences in the clay-type lithium resources between the two samples (YM-1 and YM-2) collected from Yuxi City, Yunnan Province, and the two samples (Ame-1 and Ame-2) from Nevada, USA.

RESULTSThe lithium contents of YM-1 and YM-2 and Ame-1 and Ame-2 were higher than 1000μg/g, which exhibited a certain development and utilization value. However, the clay-type lithium resource samples from the two investigated regions showed large differences in chemical composition, mineral composition, microscopic morphology, and lithium occurrences. (1) YM-1 and YM-2 had similar SiO₂ and Al₂O₃ content, with the total amount of silicon and aluminum oxides exceeding 80%, whereas Ame-1 contained 60.39% SiO₂ and Ame-2 comprised 42.30% CaO. (2) YM-1 and YM-2 were composed of kaolinite and montmorillonite, whereas Ame-1 and Ame-2 were composed of quartz, nontronite, stevensite, or calcite. (3) YM-1 and YM-2 were stacked in a layered structure with flat surfaces and had round edges and a relatively uniform size, whereas Ame-1 and Ame-2 were mainly represented by massive mineral aggregates of different sizes. (4) Montmorillonite in YM-1 and YM-2 served as the lithium source, whereas lithium in Ame-1 and Ame-2 originated from smectite minerals or illite.

CONCLUSIONSThis study elucidated the mineralogical characteristics of clay-type lithium resources in Yuxi (Yunnan, China) and Nevada (USA). It provides a scientific basis for future development and utilization of the clay-type lithium resources in these two regions.