# Microstructural Characterization of the Mn Lepidolite Distribution in Dark Red Clay Soils
## 5 Conclusions  
The obtained results clearly show that the dark red color of the forest soil samples investigated is given by the presence of the manganese lepidolite. It is present in the finest fractions containing large quantities of nanoparticles about 60 nm and microparticles up to 10 \(\upmu\)m. Sample A contains 24 wt.% lepidolite in addition to coarse fractions of quartz, kaolinite (including nanoparticles of about 40 nm), and goethite, while Sample B contains an increased amount of lepidolite around 35 wt.% in addition to moderate contents of quartz, kaolinite, and goethite.  
The washing separation process increases the lepidolite content in both Sample A and B, but the best results are obtained by Sample B, achieving the finest fraction extraction of 20.69% at a lepidolite content of 57% and a lepidolite/kaolinite ratio of 3.16. In consequence,Sample B can be suitable for further processing for lithium extraction. The yellow ground (Sample C) lacks lepidolite and is primarily composed of fine kaolinite particles combined with a significant amount of goethite.  
The recovery rate of the finest particles is highly dependent on the sedimentation process, which can be enhanced through optimal adjustment of temperature and duration--factors that warrant further investigation in future research. Simple washing cannot separate lepidolite from kaolinite fine fractions because of the lack of a specific collector or a frother agent specifically for flotation.  
Samples A and C have poor recovery of lepidolite fine fractions and, subsequently, reduced interest for further processing in extractive metallurgy but can be used for the development of ceramic glazes because of their specific colors.  
Clay particles have significant fractions able to generate PM1 and PM 2.5, while quartz can generate PM 10 emissions if the soil layer becomes excessively dry and subjected to wind erosion. The suspension of these particles in the atmosphere allows them to adhere to vehicles passing through the area, which then act as vectors, spreading the particles into more densely populated regions. Once dispersed in these areas, the particles can contribute to respiratory issues such as allergies, asthma, silicosis, and even cancer. As such, effective mitigation measures are essential.  
Conceptualization, S.E.A. and I.P.; methodology, S.E.A. and I.P.; software, G.B.; validation, S.E.A. and I.P.; formal analysis, I.P.; investigation, S.E.A., L.B.T., G.B. and I.P.; resources, S.E.A.; data curation, I.P.; writing--original draft preparation, S.E.A. and I.P; writing--review and editing, I.P.; visualization, L.B.T. and I.P.; supervision, S.E.A. and I.P.; project administration, S.E.A. and I.P. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in the study are included in the article.  
The authors gratefully acknowledge the XRD diffractometer maintenance, which was supported by the Ministry of Research, Innovation, and Digitization through Program 1-Development of the National Research and Development System, Subprogram 1.2-Institutional Performance-Funding Projects for Excellence in RDI, Contract No. 37 PFE/30.12.2021.  
The authors declare no conflicts of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} AFM & Atomic Force Microscopy \\ EDS & Energy Dispersive Spectroscopy \\ MOM & Mineralogical Optical Microscopy \\ SEM & Scanning Electron Microscopy \\ XRD & X-ray Diffraction \\ \end{tabular}