Bayerite, Al(OH)₃, from Raoul Island, Kermadec Group, South Pacific

Abstract

Abstract Bayerite forms a cascading, travertine-like deposit over volcanic tuffs on Raoul Island in the South Pacific where it is produced from episodic discharge of spent, caustic aluminate solutions from a hydrogen generator. Textural evidence indicates microbial activity has possibly been involved in formation of the hydroxide, as well as sodium carbonate aluminate, present in minor amounts. X-ray powder diffraction and infrared spectral studies failed to give confident identification of the bayerite, the identity being confirmed by laser Raman spectroscopy. A high quality spectrum was obtained extending from 3280 to 3680 cm −1 and from 100 to 1000 cm −1 .