Dehydration processes in borate minerals: pentahydroborite and nifontovite from Fuka Mine, Okayama Prefecture, Japan

Bermanec, Vladimir and Tomašić, Nenad and Žigovečki Gobac, Željka and Rajić Linarić, Maša and Furić, Krešimir (2010) Dehydration processes in borate minerals: pentahydroborite and nifontovite from Fuka Mine, Okayama Prefecture, Japan. Mineralogical Magazine, 74 (6). pp. 1013-1025. ISSN 0026-461X

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Abstract

Data on the dehydration of pentahydroborite, CaB2O(OH)6·2H2O and nifontovite, Ca3B6O6(OH)12·2H2O from the Fuka mine, Japan are presented. Critical temperatures of the dehydration of the borates were determined by thermogravimetric analysis/differential thermal analysis measurements. The untreated mineral samples and their heating products were investigated by X-ray diffraction and Raman spectroscopy. Upon dehydration, both minerals decompose and undergo amorphization, and at greater temperatures crystallize as an orthorhombic calcium borate, CaB2O4 (Pnca). The dehydration paths of the two minerals are different, with nifontovite showing a greater resistance to decomposition and amorphization than pentahydroborite. Differences in the dehydration processes are related to the residuals of the water content and structural accommodation of the borate polyanion.

Item Type: Article
Keywords: pentahydroborite, nifontovite, calcium borate, thermal decomposition, water content
Date: 2010
Subjects: NATURAL SCIENCES > Geology > Mineralogy and Petrology
Divisions: Faculty of Science > Department of Geology
Depositing User: Danica Vujičić
Date Deposited: 02 Jul 2015 10:28
Last Modified: 02 Jul 2015 10:28
URI: http://digre.pmf.unizg.hr/id/eprint/3673

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