X-ray powder refinement of a natural garnet from Diamantina, Minas Gerais, Brazil

✍ Scribed by Resende, Jackson Antônio Lamounier Camargos ;Fernandes, Nelson G.

• Publisher: International Union of Crystallography
• Year: 2005
• Tongue: English
• Weight: 192 KB
• Volume: 61
• Category: Article
• ISSN: 1600-5368
• DOI: 10.1107/s1600536805035695

✦ Synopsis

The chemical composition, [Mg 0.015 (2) ,Al 1.20 (2) ,Si 2.99 (1) ,-Ca 3.00 (2) ,Ti 0.027 (3) ,Mn 0.017 (3) , Fe 0.75 (3) ]O 12 (magnesium aluminium silicon calcium titanium manganese iron dodecaoxide), of a natural garnet collected at Diamantina, Minas Gerais, Brazil was determined by electron microprobe analysis. The structure refinement from X-ray powder data is insensitive to the small amounts of Ti, Mn and Mg. The determined cation distribution using the Rietveld method is {Ca 3

, which is in agreement with a solid solution of the grossular-andradite series. The arrangement of the cations around the O atom is best described as a highly distorted tetrahedral.