Crystal Structure and Chemical Composition of Ludwigite from Vranovac Ore Deposit (Boranja Mountain, Serbia)

• Published in: Acta geologica Sinica (Beijing) Vol. 86; no. 6; pp. 1524 - 1538
• Main Authors: TANČIĆ, Pavle, DIMITRIJEVIĆ, Radovan, POZNANOVIĆ, Maja, PAČEVSKI, Aleksandar, SUDAR, Slobodanka
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.2012; Wiley Subscription Services, Inc; Geological Institute of Serbia, Rovinjska 12, 11000 Belgrade, Serbia%Faculty of Mining and Geology, Department of Mineralogy and Crystallography, Du(s)ina 7, 11000 Belgrade, Serbia
• Edition: English ed.
• Subjects: Chemical composition; comparison; Crystal structure; Diffraction; Distortion; distortion parameters; formation temperature; ions valences; Ludwigite; M-O distances; Mathematical analysis; Mineral deposits; Mountains; ludwigite; formation temperature; comparison; distortion parameters; ions valences; crystal structure; M-O distances; chemical composition
• ISSN: 1000-9515; 1755-6724
• DOI: 10.1111/1755-6724.12020

: The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X‐ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of: a= 9.2515(2) Å; b= 12.3109(2) Å; c= 3.03712 (7) Å; and V= 345.91(1) Å3. The calculated distances and angles are mostly in good agreement with the Mg2+‐Fe2+ substitutions across the M(1) and M(3) sites, as well as with the Fe3+‐Al3+ replacement in the M(4) site. However, the mean observed M(2)‐O distance is considerably shorter than prescribed, due to a slight increase of the Fe3+ content in the M(2) site. Such replacement was compensated by slight increase of the Fe2+ content in the M(4) site, resulting in the (Mg1.48Fe2+0.46Fe3+0.05Mn0.02)2.01 (Fe3+0.94Fe2+0.04Al0.02)1.00B1.00O5 composition. The formation temperature was estimated to be about 500–600°C. The influences of the various chemical compositions to the crystallographic parameters, M‐O distances, M(3) and M(4) sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples.