Dioctahedral mica minerals with ammonium ions

Abstract

Mineralogical properties of two dioctahedral mica minerals with ammonium ions, collected from Ohgidani pottery stone deposit, Ehime Prefecture, are presented in comparison with those of a dioctahedral potassium mica mineral.
The two minerals with ammonium are characterized chemically by containing about 2 weight per cent of (NH₄)₂O and low amount of potassium, and yield four characteristic infrared absorption bands in the region from 3400 cm⁻¹ to 2800 cm⁻¹ and one band at 1430 cm⁻¹. Thermal analysis reveals that ammonium ions are driven off above 400°C before dehydroxylation of 2: 1 layer. They have larger basal reflection spacings and stronger first basal reflection than those of the potassium mica mineral, which can be explained by their bearing of interlayer ammonium in approximately equal amount to potassium.
No evidences to support the presence of hydronium ions in the present specimens have been obtained.