A Comparative Mineralogical Characterization of Structural and Skeletal Bauxites from the Kagnaka Deposit, Boké Prefecture, Republic of Guinea

“Originally published in IJSRM Human Journals”.

ABSTRACT 
Our research explored the minerals contained within six bauxite samples taken from the Kagnaka deposit, found in Guinea's 
northwestern Boké region. These samples were analyzed using X-ray diffraction (XRD). The findings showed that the samples 
could be divided into two main types: structural bauxites (three samples) and skeletal bauxites (three samples).Overall, the XRD 
tests revealed that all the samples were mainly made up of four key minerals. Gibbsite was the most common mineral, making up between 65% and 95.3% of the total material. Next came hematite, with amounts ranging from 1% to 17%, and orthoclase, found in proportions between 0.9% and 6.8%.When we compared the two types of bauxite, we found clear differences in their makeup. Structural bauxites contained much more gibbsite, averaging 87.10%, while skeletal bauxites had less, averaging 71.82%. On the other hand, skeletal bauxites showed higher average amounts of hematite (10.04%) and orthoclase (5.43%) than structural bauxites. The Lateritic Maturity Index (LMI) also highlighted these distinctions even more. Structural bauxites appeared very mature, with an average LMI of 19.67, while skeletal bauxites were less mature, with an average LMI of 5.33.Ultimately, what this tells us is that the two types of bauxite represent different stages in how laterite forms over time. Structural bauxites are from a more developed stage, while skeletal bauxites are not as developed. 
Keywords: Structural bauxite, skeletal bauxite, XRD, mineralogy and Kagnaka.