Molecular and structural investigation of yukonite (synthetic & natural) and its relation to arseniosiderite

Vibrational Spectroscopy of Complex Synthetic and Industrial Products

“…Some attempts were conducted and reported by P. M. Swash (1996) during his Ph.D. period under the supervision of A. J. Monhemius but no successful results were ever reported or published. These unsuccessful results were largely due to the fact that most of the syntheses conditions investigate by this research group were largely conducted in acidic media but as it is shown in the synthesis procedure developed by Dr. Levente Becze (Becze & Demopoulos, 2007;Gomez et al, 2010a;Becze et al, 2010), these phases are only stable at higher pH conditions (~ 8) and as such their formation also favours these environment. Once a reproducible and stable method of synthesis of these phases was developed we further investigated how the chemical distribution of the Ca, Fe, AsO 4 , OH and H 2 O were distributed among each of these Ca(II)-Fe(III)-AsO 4 phases.…”

“…Yet, in spite of all these studies and important relevance in academia as well as industry, the true molecular nature of these Ca(II)-Fe(III)-AsO 4 phases (yukonite and arseniosiderite) and how these phases were related was still not yet well understood. Therefore, a series of studies was conducted and published in this system via the use of several analytical structural and molecular techniques, of which vibrational spectroscopy was in particular an invaluable tool (Becze & Demopoulos, 2007;Becze et al, 2010;Gomez et al, 2010a).…”

Yukonite and wallkilldellite–(Fe) from the Kiura mine, Oita Prefecture, Japan

“…Then, the samples were dispersed in isopropyl alcohol and deposited on a carbon-coated 150-mesh copper microgrid. For chemical analysis, Fe is treated as trivalent in yukonite (Gomez et al, 2010) and divalent in wallkilldellite-(Fe) (Sarp et al, 1999). TEM-EDS analysis is calculated as total = 100 wt%, without considering the amount of H 2 O.…”

“…The Ca-Fe-As ratio was within the range of former studies. The yukonite was rather rich in Ca compared with the ideal formula by Gomez et al (2010), indicating wider range of composition. The low total in the EPMA analysis was likely a result of the method of sample preparation.…”

“…Another unique property of yukonite is its very wide variation in chemical composition, and various chemical formulae, such as Ca 2 Fe 3+ 3 (AsO 4 ) 3 (OH) 4 ·4H 2 O by Garavelli et al (2009) Ross and Post (1997), have been proposed. Gomez et al (2010) first described the synthetic method of yukonite and proposed an ideal formula of Ca 2 Fe 3+ 3-5 (AsO 4 ) 3 (OH) 4-10 ·xH 2 O (x = 2-11) from analysis of synthetic and natural yukonite, although they actually have some range in Ca-As ratio.…”