Classification of Nephrite Using Calibration-Free Laser Induced Breakdown Spectroscopy (CF–LIBS) with Comparison to Laser Ablation–Time-of-Flight–Mass Spectrometry (LA–TOF–MS)

Abstract

Laser induced breakdown spectroscopy (LIBS) and laser ablation–time-of-flight–mass spectrometry (LA–TOF–MS) have been employed for the identification and classification of nephrite jade from the Mohmand district of Khyber Pakhtunkhwa (KP), Pakistan. The optical emission spectrum of the laser produced nephrite jade plasma shows the spectral lines of Ca, Mg, Fe and Si as major elements along with traces of Na. Calibration-free laser induced breakdown spectroscopy (CF–LIBS) has been used for the compositional analysis of the sample. The mass spectrum of nephrite jade acquired using LA–TOF–MS confirms the presence of the same major and trace elements identified by LIBS. The Mg/(Mg + Fe) ratios calculated using both the techniques of 0.27 ± 0.08 by CF–LIBS and 0.22 ± 0.05 by LA–TOF–MS confirm that the nephrite jade from the Mohmand district of Khyber Pakhtunkhwa is of the ferro-actinolite type.