Structural state of adularia from Hishikari, Japan

Adularia sample was collected from epithermal Au-, Ag-bearing quartz-adularia veins from Hishikari, Japan. This adularia is rich in K, Or=94.63, clear, transparent, fine-grained and closely associated with quartz. In this study, it was determined by XRD, IR and²⁹Si,²⁷Al MAS NMR methods. The adularia studied is of high sanidine with triclinic domains in it. The occupancy of Al 2t₁=0.60, IR ordering θ=0.15.²⁹Si NMR spectrum of this adularia shows a broad triplet peak, i.e. 3 poorly separated peaks at −94.9, −96.7, −99.9. This kind²⁹Si NMR spectrum for natural high sanidine has never been reported before. And the²⁷Al NMR spectrum gives an asymmetry peak with chemical shift at 58.7 extending slightly to the low frequency. Under a violent boiling environment, Hishikari adularia rapidly crystallized from a supersaturated solution.