Brazil hosts the second-largest rare earth element (REE) resources worldwide, with important LREE (monazite) deposits, associated with heavy minerals as placer deposits or with alkaline-carbonatitic deposits. The latter represent a considerable technological challenge in exploiting REEs due to their frequently fine (<10 μm) grain size. Therefore, it is imperative to improve and create new techniques and procedures to assure the economic feasibility of these resources. Chemical analysis, X-ray diffraction, scanning electron microscopy and mineral liberation analysis were performed on two different samples with low and high LREE contents from Catalão (Goiás, Brazil). All the results presented herein are thus a necessary first step to develop concentration test protocols to improve monazite recovery during mineral processing. According to these mineralogical results, the monazite’s concentration might make recovery feasible despite its fine-grained size. MLA showed that barite is mainly concentrated in the coarser size fractions for both samples, whereas monazite is liberated below 75 μm for low-grade ore and below 150 μm for high-grade ore, suggesting that a sieving procedure could reduce it to nearly 30%–50% of the total mass of the samples, with barite and quartz reduction from 53% to 57% and 54%–65%, respectively.