Hagendorfite (Na,Ca)MnFe (sub 2) (PO (sub 4) ) (sub 3) from type locality Hagendorf (Bavaria, Germany); crystal structure determination and (super 57) Fe Moessbauer spectroscopy
Hagendorfite (Na,Ca)MnFe (sub 2) (PO (sub 4) ) (sub 3) from type locality Hagendorf (Bavaria, Germany); crystal structure determination and (super 57) Fe Moessbauer spectroscopy (in Micro- and mesoporous mineral phases, S. Merlino (editor))
European Journal of Mineralogy (December 2005) 17 (6): 915-932
The crystal structure of hagendorfite from the type locality has been determined and found to be isostructural with alluaudite; the hagendorfite has a 11.9721, b 12.5988, c 6.5029 Aa, beta 114.84 degrees , V 890.11 Aa (super 3) , Z = 4, space group C2/c. The specific arrangement of M 1 and M 2 octahedral sites and of P1 and P2 tetrahedral sites gives rise to two different channels aligned along the crystallographic c axis, containing the A1 and A2 sites. In both alluaudite and hagendorfite the A1 site is fully occupied and shows a mixed occupation of Na (super +) , Ca (super 2+) and Mn (super 2+) (hagendorfite) and Ca (super 2+) and Na (super +) in alluaudite.The A2 site is fully occupied by Na (super +) in hagendorfite and parly filled by 0.14 Na (super +) in the Buranga alluaudite. The structural topology of hagendorfite is described in detail and its structural parameters compared with alluaudite. The (super 57) Fe Moessbauer spectroscopy shows that iron is exclusively in the trivalent state in alluaudite, while in hagendorfite approximately (super 2) / (sub 3) of the total iron is divalent. The ferrous iron resonance absorption contribution appears to be broad and can only be refined with four different Fe (super 2+) subcomponents, all ascribed to the M 2 site.