A massive deposit of the natural mineral illite, evaluated as the world's largest, has been confirmed in Yeongdong, North Chungcheong Province, drawing attention to its industrial potential. Beyond sheer scale, the deposit's quality and range of applications have been verified, giving it significance as a future resource for the region.
"100 Million Tons Reserved"... World's Largest-Class Illite Deposit Confirmed
According to Yeongdong County on Tuesday, a joint "Illite Mine Reserve Survey" conducted with the Korea Institute of Geoscience and Mineral Resources (KIGAM) estimated the area's total illite reserves at approximately 104.5 million tons. This exceeds the standard for a typical large clay deposit (about 5 million tons) by more than 20 times, making it exceptionally large on a global scale. Given that major illite deposits overseas, including those in China, hold reserves of only a few million tons, the scale is overwhelming.
The survey was conducted by analyzing the range and content of deposits through 28 boreholes. The results showed that 67.7% of the total reserves are distributed in the 40–45% grade range, indicating high industrial utility. In particular, the potential as a functional material was proven by the confirmation of high illite content reaching up to 98% on a fine-particle basis, along with excellent mineralogical properties.
Where Is the "Mystery Mineral" Illite Used?
Illite is a type of clay mineral first discovered in Illinois, United States, in 1937, from which it took its name. It is called the "mystery mineral" due to its diverse properties, including heavy metal adsorption, antibacterial and deodorizing effects, reduction of harmful substances, and far-infrared emission.
Thanks to these characteristics, its range of applications is rapidly expanding beyond construction materials, fertilizers, and animal feed to cosmetics, health functional foods, and environmental materials. Recently, its plant growth-promoting effects have also been confirmed, attracting attention in the agricultural sector. In fact, research found that bean sprouts cultivated using illite contained 1.9% and 11.2% more vitamin C and minerals, respectively, compared to those grown conventionally.
The discovery also holds geological significance. Illite in the Yeongdong area is widely distributed across a shear zone 500–600 meters wide along the southeastern section of the Yeongdong Fault, with seven ore bodies confirmed in Jugok-ri, Yonggung, Sanik-ri, Dongchang, Jukchon-ri, Medex, and Namjeon-ri. The deposit is analyzed to have formed through a combination of shear zone formation and subsequent alteration caused by fluid infiltration.
Yeongdong County: "We Will Grow It Into a 100-Year Future Industry"
In fact, the potential of Yeongdong illite has long been recognized. After reserves were first confirmed in 1985, KIGAM investigated its quality in 2007 and acknowledged its high utility. In particular, a 2022 survey raised the possibility of a large-scale deposit of about 500 million tons, earning it recognition as a world-class resource. Local mining companies currently extract about 2,500 tons annually — an amount that, by simple calculation, could sustain operations for hundreds of thousands of years or more.
Since securing mining rights to 15 mining areas (approximately 2,030 hectares) in the region in 2017, Yeongdong County has been working to foster related industries. The mineral is currently used in the production of cosmetics, fertilizers, construction materials, and animal feed, and expansion into food additive registration as well as pharmaceutical and quasi-drug applications is also under review.
Based on the survey results, the county plans to develop the illite industry into a high-value-added sector by establishing standardization and certification systems and expanding corporate support. "We have objectively confirmed the potential for illite to grow into a world-class strategic mineral resource," a Yeongdong County official said. "We will develop Yeongdong into the global center of the illite industry."
