Danburite structure

Danburite is calcium borosilicate with an orthorhombic structure (2/m2/ mljm) and space group Pnam. The natural danburite in our study consisted of five samples from a variety of geologic environments. Concentrations of potential luminescence impurities in one sample are presented in Table 4.8. 

Beran A. (1987) OH groups in nominally anhydrous framework structures an infrared spectroscopic investigation of danburite and labradorite. Phys. Chem. Mineral. 14, 441-445. 

Infrared Spectroscopy. Infrared spectroscopy has been used to study borosilicate molecular sieves (22.25.33-361. Vibrational bands associated with trigonal framework boron occur near 900 cm"1 and 1400 cm 1 (22.25.331. The presence of the Si-0-B asymmetric stretching vibration, indicative of tetrahedral framework boron incorporation, cannot be observed directly because it is masked by the strong Si-0-Si band near 1100 cm-1 in the pentasil structures. The tetrahedral Si-O-B vibration has been observed for the borosilicate mineral danburite (.33). Shifts of bands in the framework vibrational region at 550 cm"1 and 560 cm"1 to higher frequencies as a function of boron content has been used to study boron incorporation in the framework of AMS-1B borosilicate (36). 

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