A spectrographic method has been developed to enable a survey to be made of the boron content of acid rocks from the central volcanic zone of the North Island of New Zealand. The concentrations of boron in the rocks were in the range 0-100 ppm.
J. R. Sewell, "Si-O Band Suppression in the Spectrographic Analysis of Silicate Rocks for Boron," Appl. Spectrosc. 17, 166-167 (1963)