Handheld LIBS for Lithium Exploration: An Example from the Carolina Tin-Spodumene Belt, USA

Publication: Michael A. Wise, Russell S. Harmon, Adam Curry, Morgan Jennings, Zach Grimac and Daria Khashchevskaya. “Handheld LIBS for Li Exploration: An Example from the Carolina Tin-Spodumene Belt, USA,” Minerals 2022, 12, 77.

A wide variety of samples from the Carolina Lithium Project prospect were analyzed on site during 21–22 October 2021, either at the core storage facility or at field outcrops that included minerals in the drill core and outcrop, the pulverized drill core, and the soil. Minerals analyzed included spodumene, muscovite, quartz, albite, K-feldspar, tourmaline, and vivianite. Here, in-field LIBS analysis of pegmatite outcrops shows the use of the handheld LIBS analyzer for in-situ analysis (a) and examples of the different minerals analyzed—feldspar (b); feldspar, quartz, spodumene, and tourmaline (c); spodumene (d); and quartz (e).

‍Abstract: Laser-induced breakdown spectroscopy (LIBS), which has recently emerged as tool for geochemical analysis outside the traditional laboratory setting, is an ideal tool for Li exploration because it is the only technique that can measure Li in minerals, rocks, soils, and brines in-situ in the field. In addition to being used in many products essential to modern life, Li is a necessary element for a reduced carbon future and Li–Cs–Ta (LCT) granitic pegmatites are an important source of Li. Such pegmatites can have varying degrees of enrichment in Li, Rb, Cs, Be, Sn, Ga, Ta>Nb, B, P, and F. We focus here on the LCT pegmatites of the Carolina Tin-Spodumene Belt (CTSB) situated in the Kings Mountain Shear Zone, which extends from South Carolina into North Carolina. The CTSB hosts both barren and fertile pegmatites, with Li-enriched pegmatites containing spodumene, K-feldspar, albite, quartz, muscovite, and beryl. We illustrate how handheld LIBS analysis can be used for real-time Li analysis in the field at a historically important CTSB pegmatite locality in Gaston County, N.C. in four contexts: (i) elemental detection and identification; (ii) microchemical mapping; (iii) depth profiling; and (iv) elemental quantitative analysis. Finally, as an example of a practical exploration application, we describe how handheld LIBS can be used to measure K/Rb ratios and Li contents of muscovite and rapidly determine the degree of pegmatite fractionation. This study demonstrates the potential of handheld LIBS to drastically reduce the time necessary to acquire geochemical data relevant to acquiring compositional information for pegmatites during a Li pegmatite exploration program.

‍Access to publication: https://doi.org/10.3390/min12010077

‍About this journal: Minerals is an international, peer-reviewed, open access journal of natural mineral systems, mineral resources, mining, and mineral processing. Minerals is published monthly online by MDPI.