Ann: StepOut Drilling Multiplies Cupim South High-Grade Footprint, page-26

From the above article:

The majority of economically exploited IADs occur in Southern China, where the REEs are hosted in the weathered crusts of igneous, mostly granitic, bedrock^7,8,12. They account for c. 35% of China’s total REE production and roughly 80% of global HREE supplies^4,6, despite being low grade (0.05–0.2 wt% total RE₂O₃, incl. Y₂O₃) and relatively low tonnage compared to hard-rock REE deposits associated with carbonatites and alkaline igneous rocks^1,14. Economic exploitation of IADs is viable through REE extraction by low-cost in situ or heap leaching^8,12,15, a process that has had significant environmental impact in China⁶. The key requirement is that the majority of REEs are readily liberated using ionic solutions and are hence ion exchangeable¹⁰.