ASSESSMENT OF LI AND REE IN ORDOVICIAN K-BENTONITE FROM CENTRE COUNTY PENNSYLVANIA

As the development of modern products and technology increases, the production of critical minerals like lithium and rare earth elements has become essential in sustaining the United States economy and quality of life. Mineral resources are unevenly distributed in the world and availability of resources are also governed by international politics and environmental regulatory policy. This creates a focus on researching domestic mineral resources, mining, and processing methods.

Bentonite is an important natural resource because it has many useful applications and is a possible source of the critical element lithium. Lithium is needed in order to fulfill sustainability plans that include electric cars and other demands for lightweight battery power. Bentonite has other useful applications such as metal casting, pet waste absorbents, drilling fluids, iron ore pelletizing, bleaching, clarifying, desiccants, paper making, and environmental sealants. Bentonite is a natural clay composed mainly of montmorillonite. Montmorillonite is responsible for bentonites economically relevant characteristics, such as large surface area, negative charge, and counter-balancing exchangeable surface cations.

This study focuses on extensive Ordovician K-bentonite beds outcropping in Pennsylvania and across North America. These deposits extend over 600,000 km2 , and represent >1,000 km3 of material. Previous studies have shown that K-bentonites can be enriched in lithium. The focus of this study is to determine lithium and REE concentrations in our bentonite samples, and to assess whether lithium contents in bentonite can be linked to the original magmatic source. Lithium and REE concentrations were determined in zircons separated from the Deicke and Millbrig bentonites using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). We discovered that lithium in our zircons is relatively low compared to other studies. This doesn’t necessarily mean lithium in bentonite is low, because lithium can be adsorbed onto clay surfaces by hydrothermal circulation after the ash layer has been altered. Future analysis of the bulk clay samples will determine whether lithium was concentrated in the K-bentonite layers after deposition and alteration.