Boron determination in tourmaline by neutron induced radiography

Abstract

The technique of neutron induced radiography has been applied to determine the boron concentration and its spatial distribution in mineral tourmaline collected from Swat Tourmaline Granite, Northern Pakistan. The technique involves the simultaneous irradiation of sample and a standard fixed on a track detector with thermal neutrons and the counting of alpha and 7 Li tracks produced in the detector from the nuclear reaction 10 B( n,α) 7 Li . Boron concentration is determined by comparing the 7 Li and alpha particle tracks density with that of a standard of known boron concentration. Boron concentration in tourmaline has been found to be (3.40±0.01)% in this study which is on the upper side within the normal range (2.5–3.8)% reported in the world. The presence of somewhat higher concentration of boron in tourmaline indicates that the Swat Tourmaline Granite was generated as a late stage hydrothermal activity during the Himalayan Orogeny.