IDENTIFICATIONS ON PURE AND FAKED PEARL LAYER POWDER USING X-RAY DIFFRACTION AND ELECTRON SPIN RESONANCE

Dayong Lu, Shuai Kang

ABSTRACT:The high-grade commercially available pearl layer powder (CAPLP, 80 yuan a bottle) and the cheap street pearl powder (CSPP, 10 yuan a bottle) were investigated using X-ray diffraction (XRD) and electron spin resonance (ESR) techniques. The major constituent of CAPLP was identified to be pure pearl powder composed of calcium carbonate (CaCO3) with an orthorhombic crystal structure, which should be fabricated by grinding freshwater pearls. CSPP was identified by XRD to be a mixture of scallop shell powder (78 %) and pearl powder (22 %), and therefore CSPP was a fake and shoddy commodity. The major constituent of scallop shell was CaCO3 with a monoclinic crystal structure. The ESR results demonstrated that the concentration of Mn2+ in CAPLP is lowest and that is highest in scallop shell. The ESR also detected Fe impurities in CSPP. The combination of XRD and ESR techniques can set up a rapid detection method for quality control of CAPLP.

Keywords:Pearl powder, X-ray diffraction, crystallized phase, electron spin resonance.