III. Über eine hydrothermale Paragenesis von Quarz und Arsenmineralien im veränderten Quarzporphyr vom Saubach i. V. und über einige Eigenschaften des Pharmakosiderits und des Symplesits.

Heide, F. R. Van Der

doi:10.1524/zkri.1928.67.1.33

Cited by 6 publications

(4 citation statements)

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“…Other possible hydrogen-bond contacts are listed in Table 8. Some of the water of crystallization is "zeolitic" in nature, a fact noted by earlier workers (Hartley 1899, Heide 1928, Mutter et al 1984).…”

Section: Resultsmentioning

confidence: 78%

“…Thus it is clear that the pharmacosiderite group hosts a family of stoichiometries, as well as a range of structures. Finally, it is noted that color variation in the group is well known, ranging from pale yellow or green to deep orange, red and red-brown (Hartley 1899, Heide 1928, Palache et al 1951, Mutter et al 1984). This must arise by a change of the Fe 3+ ion chromophore, and this cannot be achieved by deprotonating lattice H 2 O molecules in the structure.…”

Section: Resultsmentioning

confidence: 99%

“…Similarly, Buerger et al (1967) reported a single-crystal structural study confirming the basic lattice structure, but noted that the structure in space group P43m is averaged, and the K atoms could not be found. Furthermore, a spectrographic analysis failed to reveal the presence of any alkali metals; it may be that the crystal studied was in fact the hydronium analogue, known previously from ion-exchange studies (Hartley 1899, Heide 1928, Mutter et al 1984. The careful study by Mutter et al (1984) did resolve ambiguities associated with reported anomalous optical properties and showed that pharmacosiderite and its congeners could crystallize in four related space groups; two are cubic, P43m and I43m, with a ≈ 8 and 16 Å, respectively, and two are M7966) were analyzed (n = 5) with an electron microprobe (EMP) (WDS mode, 15 kV, 20 nA, 5 mm beam diameter).…”

Section: Methodsmentioning

confidence: 95%

“…The slight excess positive charge of (Ba 0.51 K 0.04 Na 0.02 ), alternatively, could be accommodated by deprotonation of a small proportion of the bridging OH groups. It is also worth noting that the range of analytical data indicates that the crystals are chemically inhomogeneous, a feature of a number of naturally occurring members of the pharmacosiderite group (Hartley 1899, Heide 1928, Mutter et al 1984, Mills et al 2010b). In the structure refinement, the Ba site was fixed at (Ba 0.47 K 0.04 Na 0.02 ) with total charge equal to 1+, but this has no effect on the structural conclusions that are reached.…”

Section: Methodsmentioning

confidence: 99%

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THE SINGLE-CRYSTAL X-RAY STRUCTURES OF BARIOPHARMACOSIDERITE-C, BARIOPHARMACOSIDERITE-Q and NATROPHARMACOSIDERITE

Hager¹,

Leverett²,

Williams³

et al. 2010

The Canadian Mineralogist

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The crystal structures of two polymorphic forms of bariopharmacosiderite have been determined. Bariopharmacosiderite-C, from Robinson's Reef, Clunes, Victoria, Australia, (Ba 0.47 K 0.04 Na 0.02 )(Fe 3.97 Al 0.03 )[(As 0.72 P 0.28 )O 4 ] 3 (OH) 4 •2.52H 2 O, is cubic, space group P43m, a 7.942(1) Å, Z = 1, R = 0.089. Bariopharmacosiderite-Q, from the Sunny Corner mine, Sunny Corner, New South Wales, Australia, Ba 0.5 Fe 4 (OH) 4 (AsO 4 ) 3 •6.16H 2 O, is tetragonal, space group P42m, a 7.947(1), c 8.049(2) Å, Z = 1, R = 0.050. In the cubic polymorph, Ba ions are disordered over all faces of the unit cell, whereas in the tetragonal polymorph, Ba ions are centered on the 001 face. In both cases, the Ba ions are 12-coordinate, with eight bonds to arsenate oxygen atoms; four H 2 O groups complete the coordination sphere, with longer bonds to Ba in the cubic polymorph. Additional H 2 O groups are hydrogen-bonded to each other and to the H 2 O groups that coordinate Ba. Some of these exhibit "zeolitic" behavior. By analogy to the properties of synthetic pharmacoalumite, KAl 4 (AsO 4 ) 3 (OH) 4 •nH 2 O, the cubic polymorph appears to be more stable than the tetragonal one, although two further body-centered polymorphs are known. In addition, the crystal structure of natropharmacosiderite from the Gold Hill mine, Utah, has been determined. Natropharmacosiderite, (Na 0.75 K 0.14 Ba 0.11 ) S1.00 Fe 4 (AsO 4 ) 3 (OH) 3.89 O 0.11 •4H 2 O, is cubic, space group P43m, with a 7.928(9) Å, Z = 1 and R = 0.0654. The Na position is displaced by ~0.2 Å from the Wyckoff 3c site, and is coordinated by four H 2 O groups and eight oxygen atoms of arsenate groups. A new general formula for "excess cation" pharmacosiderite is proposed, involving deprotonation of bridging hydroxide ions.

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Section: Resultsmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%