Mineralogical composition and functionality of clays used for pottery education by physically challenged learners at the Ikwezi-Lokusa Educational Centre, Eastern Cape, South Africa

Abstract

Clays used for pottery education to physically challenged learners were mineralogically analysed to appraise their suitability both for usage in making pottery products and convenience for the learners. The suitability is alluded to the fact that the clays have undergone basic beneficiation which include grinding, removal of unwanted materials through sieving, prior to their usage. The clays were mineralogically characterised using Munsell Soil Color Chart, X-ray powder diffractometry (XRPD) and optical microscopy. Results revealed that the color of the samples were light yellow brown to white. Mineral phases identified by XRPD depicted both quartz (SiO₂) and kaolinite as the dominant minerals in the samples with traces of smectite ((Na,Ca)(Al,Mg)₆(Si₄O₁₀)₃(OH)_6-n(H₂O)), mica (AB_2-3(Al,Si)Si₃O₁₀)(F,OH)₂) and feldspar (Na/K(AlSi₃O₈)). Optical morphology tests depicted quartz particles were generally coarse; and angular to very angular in morphology. Due to the beneficiation process the quartz particles were reduced making the clays easy to handle during both creation and firing stages of the pottery making. The mineralogical composition of the clays influenced their functionality as raw materials for pottery.

Keywords: Clay processing, color, disability, kaolinite, quartz, X-ray powder diffraction.