Sanjuanite: Ab Initio Crystal-Structure Solution From Laboratory Powder-Diffraction Data, Complemented by Ftir Spectroscopy and Dt-Tg Analyses

Source and genesis of sulphate and phosphate–sulphate minerals in a quartz‐sandstone cave environment

“…The first occurrence of sanjuanite in Argentina (De Abeledo et al, 1968) shows the same mineralogical association with gypsum and alunite as that found in the Akopan tepui (this study), developing however in remarkably different environments: Carboniferous-Ordovician limestone bedrock and arid climate in Argentina, and Precambrian quartz-sandstone in tropical wet conditions in Venezuela. Unfortunately, the original site of discovery in the San Juan province can no longer be found (Colombo et al, 2011) and therefore a detailed comparison is impossible. However, in the last two years, sanjuanite was discovered not only in the Akopan-Dal Cin System (this study) but also in two other caves of the tepui mountains: the Muchimuk cave system (Aubrecht et al, 2012) and, in large amounts, in the recently discovered Imawar ı Yeuta Cave in the Auyan Tepui (Sauro et al, 2013c).…”

“…De Abeledo et al (1968) suggested a hydrothermal origin for sanjuanite with ascending acidic solutions. Colombo et al (2011) suggested instead that the origin of sulphur in sanjuanite could be related to weathering under arid conditions of syngenetic sulphides, like pyrite in pelites or in Fe 3+ oxy-hydroxide veins. Aubrecht et al (2012) disagreed with such hypotheses, suggesting instead a probable origin from guano or accumulation of dead animal bodies, at least for the sanjuanite found in quartz-sandstone caves.…”

“…Colombo et al . () suggested instead that the origin of sulphur in sanjuanite could be related to weathering under arid conditions of syngenetic sulphides, like pyrite in pelites or in Fe 3+ oxy‐hydroxide veins. Aubrecht et al .…”

ASb2(SO4)2(PO4) (A = H3O+, K, Rb): Layered Structure Containing Ordered Sulfate and Phosphate Anions

“…Among these compounds, only 38 sulfate‐phosphate compounds have been reported since Svanbergite SrAl 3 (PO 4 )(SO 4 )(OH) 6 3 was first found in 1947. Their structures exhibit different dimensionalities, such as three‐dimensional framework in β‐Zr 2 (PO 4 ) 2 (SO 4 )4,5 SrAl 3 (PO 4 )(SO 4 )(OH) 6 and CaAl 3 (PO 4 )(SO 4 )(OH) 6 ,3 and Pb 2 Cu(PO 4 ) 2 (SO 4 )(OH),6 two‐dimensional layered in [Fe(H 2 O) 2 (PO 3 OH)] 2 (SO 4 ) · 1–2H 2 O,7 Al 12 Fe 2 (PO 4 ) 11 (SO 4 )(OH) 7 · 83H 2 O,8 Al 5 (PO 4 )(SO 4 )(OH) 10 · 8H 2 O,9 and Na 3 Al 16 (PO 4 ) 10 (SO 4 ) 2 (OH) 17 · 20H 2 O,10 one‐dimensional chains in Al 3 (PO 4 )(SO 4 ) 2 (OH) 2 (H 2 O) 10 · 4H 2 O,11 Al 2 (PO 4 )(SO 4 )(OH) · 9H 2 O 12. Isolated anionic units are observed only in alkali metal hydrogen sulfate‐phosphates, for instance, K 2 (HSO 4 )(H 2 PO 4 ),13 Rb 4 (HSO 4 ) 3 (H 2 PO 4 ),14 Cs 3 (HSO 4 ) 2 (H 2 PO 4 ),15,16 Cs 5 (HSO 4 ) 3 (H 2 PO 4 ) 2 ,17 and Cs 2 (HSO 4 )(H 2 PO 4 ) 18.…”

Camaronesite, [Fe3+(H2O)2(PO3OH)]2(SO4)·1–2H2O, a new phosphate-sulfate from the Camarones Valley, Chile, structurally related to taranakite

“…In spite of the abundance of Fe, S and P in the natural environment, only two minerals, destinezite, and its amorphous analogue, diadochite, are known, with only these cations (Peacor et al, 1999;Mills et al, 2012). Several other minerals contain phosphate and sulfate ions; however, many of these minerals are members of the alunite supergroup (Mills et al, 2009;Bayliss et al, 2010) or complex white Al phosphateÀsulfates such as peisleyite (Mills et al, 2011), sanjuanite (Colombo et al, 2011), hotsonite (Beukes et al, 1984, kribergite (de Bruiyn et al, 1989) and sasaite (Martini, 1978).…”