This ceramic is made from high-purity alumina.
bauxite
gedrite
The kanji 礬 (ばん) originally referred to alum, and 土 (ど) means earth or soil. The compound 礬土 was coined in Japanese scientific terminology to denote alumina, the earthy substance derived from alum. The exact historical derivation is uncertain, but the term follows the pattern of early modern chemical nomenclature using kanji.