Rietveld structure refinement of the apophyllite crystals from Deccan Basalt Plateau using X-ray powder diffraction data

Abstract

The crystal structure of a rare sample of natroapophyllite from Pune district (western India) located in the Deccan Basalt Plateau has been refined using X-Ray powder diffraction data and the Rietveld method. The Rietveld refinement was carried out using the computer program Diffracplus TOPAS 4.1. The pseudo-Voigt (pV) profile function was used for the fit of the peaks. The Rietveld refinement of the analyzed sample in space group Pnnm (No.58): a=8.94771 Å, b=8.98013 Å, c=15.78878 Å, Z=2, confirm the basic natroapophyllite structure. The chemical composition of the apophyllite crystals from Pune region (India) was determined by EDX analysis. The paper presents a new set of the unit cell parameters and fractional coordinates that define the natroapophyllite crystal structure. The quality of the sample analyzed was pristine, the sample being collected from an association of apophyllite-stilbite crystals of centimetric dimensions.