Boron in Magnesium Minerals of the Humite Group

摘要

Based on microprobe analysis and IR-spectroscopy of a representative collection of magnesium minerals of the humite group (282 samples from 80 various geological–genetic occurrences all over the world), it was shown for the first time that these minerals typically concentrate trace boron (from 0.5 to 4.9 wt % B_2O_3 in 63 samples). The diagnostic bands of B–O stretching vibrations in IF-spectra of magnesium minerals of the humite group occur within the 1170–1190, 1262–1289, and 1306–1331 cm~(–1) ranges and are regularly shifted to the low frequencies in a norbergite–chondrodite–humite–clinohumite series. Boron iso-morphically replaces silicon in tetrahedra, probably, by Pertsev’s scheme: Si~(4+) + O~(2–) → B~(3+) + (F,OH)~–.