Jarosites structure

The fundamental chemistry associated with the thermodynamics of formation of the alkali jarosites (M = Na, K or NH4) has been studied, and it has been found that substitution of the alkali ions by Ag" " or 1 /2 Pb + produces jarosites that are often formed during the processing of lead or zinc ores, which generally contain silver as a valuable byproduct. In addition, partial or complete substitution of iron(III) by divalent metal ions can occur, resulting in the formation of an extensive range of substituted jarosites such as beaverite, PbCuFe2(S04)2(0H)e. The order of incorporation into the lead jarosite structure has been found to be Fe + > Cu " " > > Co " "... 

Fig. 8.34 Lefty, outcrop rocks found at the crater wall of Eagle Crater, where the rover Opportunity landed on 24 January 2004. Clearly, the sedimentary structure is seen. Right) in the spectrum, taken on sol 33 (sol = Martian day) of the mission, the mineral Jarosite, an Fe -sulfate, could be identified at the Meridiani Planum landing site. It forms only under aqueous conditions at low pH (< 3 ) and is therefore clear mineralogical evidence for aqueous processes on Mars...

Arsenate commonly substitutes for sulfate and phosphate in a variety of minerals and other solid compounds. Jarosite is an example of a sulfate mineral that may acquire considerable arsenate through substitutions into its crystalline structure. Jarosites often precipitate in acid mine drainage and they could be important in controlling the mobility of arsenate in these waters (Chapter 3). 

Structure-type corundum spinel ramsdellite hollandite lepidocrocite smectite jarosite... 

Menchetti, S. Sabelli, C. (1976) Crystal chemistry of the alunite series Crystal structure refinement of alunite and synthetic jarosite. Neues Jahrb. Mineral. Mh, pp. 406-17. 

Despite these limitations, the technique has been applied in the past to characterize the forms of iron occurring in different plants [62-65]. More recently, a detailed study of iron uptake and translocation in rice [66] grown in anaerobic FeCb-enriched nutrient solutions showed primarily the presence of Fe(lll) hydrous oxide components precipitated on the root cell wall (ferrihydrite and/or lepidocrocite). No evidence of Fe(ll) was found in the leaf tissue, the spectra were characteristic of Fe(lll) present in ferritin and in other complexed forms, not further identified by the authors. Iron biomineralization was also observed In a perennial grass grown in extreme acidic environment with a high content of metals [67,68]. In this case, the Mossbauer spectral analysis indicated that iron accumulated in this plant mainly as jarosite and ferrihydrite (ferritin). ]arosite accumulated In roots and rhizomes, while ferritin was detected in all the structures. 

Jarosite is a mineralogical marker for aqueous processes because it contains the equivalent of 10 wt. % H2O in its structure as the OH anion. The average S-rich outcrop rock at Meridiani Planum has the equivalent of 2 % H2O associated with jarosite alone. An important aspect of the jarosite detection is that acidic conditions (pH < 4 at room temperature) are required for its formation. The alteration of basaltic precursor material under oxidizing, acid-sulphate conditions to form jarosite and other phases in the S-rich outcrop rocks at Meridiani Planum could have occurred under conditions provided, for example, by interactions with acid-sulphate, possibly hydrothermal waters and/or condensation of S02-rich volcanic emanations [91]. 

Wills Harrison (1996) Wills, A.S. Harrison A. Structure and magnetism of hydronium jarosite, a model Kagome antiferromagnet Journal of the Chemical Society -Faraday Transactions 92 12 (1996) 2161-2166 WmcHELL (1931) Winchell, A.N. The Microscopic Characters of Artificial Inorganic Solid Substances or Artificial Minerals 2nd ed., John Wilq Sons, New York (1931)... 

Figure 2.14 The jarosite, AM3(S04)2(OH)s, structure. The MOg units are shown as octahedra, the anions as tetrahedra and the A+ cations as spheres. The H...

The intraplanar spin structure of the iron jarosites is described by the so-called k=(00) structure. Figure 2.16, left, rather than the k = (yi/3 yi/3) structure, right, in spite of both classical and quantum theories for the kagome lattice which predict the latter. ... 

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