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  • Mineralogical Society  (4)
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  • Mineralogical Society  (4)
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  • 1
    Online Resource
    Online Resource
    On the new mineral theophrastite, a nickel hydroxide, from Unst, Shetland, Scotland
    Mineralogical Society ; 1982
    In:  Mineralogical Magazine Vol. 46, No. 338 ( 1982-03), p. 1-5
    Details
    In: Mineralogical Magazine, Mineralogical Society, Vol. 46, No. 338 ( 1982-03), p. 1-5
    Abstract: The new mineral theophrastite, Ni(OH) 2 , from Unst, is Mg-bearing and occurs associated with a very poorly crystalline Ni-containing mixed hydroxide of the pyroaurite type and/or zaratite on chromitite. X-ray powder diffraction data show a shift in d spacing toward brucite compared with pure Ni(OH) 2 . Infrared, thermal, chemical, optical, and physical data are presented together with indexed powder data for fifteen lines ranging from d 4.66Å to 0.90Å. The solid-solution series brucite-theophrastite is briefly discussed.
    Type of Medium: Online Resource
    ISSN: 0026-461X , 1471-8022
    URL: Article
    DOI: 10.1180/minmag.1982.046.338.01
    RVK:
    TE 1000
    Language: English
    Publisher: Mineralogical Society
    Publication Date: 1982
    detail.hit.zdb_id: 2034522-7
    SSG: 13
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    The combined use of steam-treated bentonites and natural zeolites in the oenological refining process
    Mineralogical Society ; 2016
    In:  Mineralogical Magazine Vol. 80, No. 2 ( 2016-04), p. 347-362
    Details
    In: Mineralogical Magazine, Mineralogical Society, Vol. 80, No. 2 ( 2016-04), p. 347-362
    Abstract: Industrial minerals, particularly bentonites, have long been used in treatments to improve the stability and shelf life of white wines. We evaluated a new combination of rocks and minerals, including steam-treated bentonites and natural zeolites (chabazite and phillipsite), to greatly reduce the risk of protein and tartaric instability of wines. Detailed mineralogical, chemical and electrokinetic studies of these materials were conducted using powder X-ray diffraction (PXRD), X-ray fluorescence (XRF), microporosimetry, BET surface-area analysis and zeta-potential measurements. Several model wine solutions containing Bovine Serum Albumin (BSA) were prepared to evaluate the oenological performance of the rock/mineral combinations. UV-VIS spectrophotometry and ion chromatography were used to evaluate the degree of wine stabilization from the protein and tartaric point of view. The experimental results showed that steam treatment modifies both the microporosity and external surface area of the bentonite. These changes in surface area, along with creation of hydrophobic surfaces, significantly modified the behaviour of the steam-treated bentonites, requiring an increase in the amount of material necessary to bring the protein content to required levels. An important benefit derived from the use of steam-treated bentonites is that the pre-mixing with water before addition to wine is not necessary, as the material is readily dispersed. Finally, the addition of natural zeolites effectively decreased the potassium content, thereby improving the tartaric stability of white wines. In addition, this procedure results in minimal waste, as the bentonite-zeolite mixture can be reused as soil amendments in agriculture.
    Type of Medium: Online Resource
    ISSN: 0026-461X , 1471-8022
    URL: Article
    DOI: 10.1180/minmag.2016.080.004
    RVK:
    TE 1000
    Language: English
    Publisher: Mineralogical Society
    Publication Date: 2016
    detail.hit.zdb_id: 2034522-7
    SSG: 13
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Mineralogical and sulphur isotopic evidence for the influence of sulphatereducing and -disproportionating bacteria on pyrite and marcasite formation in the Georgia kaolins
    Mineralogical Society ; 2012
    In:  Clay Minerals Vol. 47, No. 4 ( 2012-12), p. 559-572
    Details
    In: Clay Minerals, Mineralogical Society, Vol. 47, No. 4 ( 2012-12), p. 559-572
    Abstract: The Georgia, USA, kaolins contain three major occurrences of Fe-sulphide minerals, namely (1) in burrow structures, (2) as nodules associated with lignite and (3) as finely disseminated material. We have used sulphur isotope analysis and X-ray powder diffraction to understand these three occurrences in order to gain insight into the diagenetic conditions and microbial influences affecting the kaolin mineralogy. Burrows and nodules are dominated by corroded marcasite with thin pyrite overgrowths. The δ 34 S composition of each sulphide sample has internal fractionations (δ 34 Shigh – δ 34 Slow) ranging from 22‰ to 67‰. The secondary pyrite phase tends to be the most 34 S depleted, with a low δ 34 S value of –47‰, whereas marcasite displays a δ 34 S range from 30‰ to +33‰. Early acidic environments from organic acids could have facilitated the initial marcasite crystallization, with a pH increase during later diagenesis producing pyrite overgrowths. Sulphide formation would have continued until burial restricted the diffusion of sea-water sulphate. At this point, the metabolism of sulphate-reducing bacteria would have been retarded, producing δ 34 S values ranging from –30‰ (open sulphate supply) to +40‰ (highly restricted sulphate supply). Under the nutrient-starved conditions of later-diagenesis, disproportionate sulphur-reducing bacteria would likely have become more dominant, yielding additional δ 34 S sulphide fractionation and producing the observed fractionation (δ 34 S sulphate – δ 34 S sulphide ) values of +67‰.
    Type of Medium: Online Resource
    ISSN: 0009-8558 , 1471-8030
    URL: Article
    DOI: 10.1180/claymin.2012.047.4.11
    RVK:
    TE 1000
    Language: English
    Publisher: Mineralogical Society
    Publication Date: 2012
    detail.hit.zdb_id: 2036186-5
    detail.hit.zdb_id: 961059-5
    SSG: 13
    Location Call Number Limitation Availability
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    Online Resource
  • 4
    Online Resource
    Online Resource
    The crystal chemistry and paragenesis of honessite and hydrohonessite: the sulphate analogues of reevesite
    Mineralogical Society ; 1981
    In:  Mineralogical Magazine Vol. 44, No. 335 ( 1981-09), p. 339-343
    Details
    In: Mineralogical Magazine, Mineralogical Society, Vol. 44, No. 335 ( 1981-09), p. 339-343
    Abstract: Honessite and hydrohonessite from Unst, Shetland, and Linden, Wisconsin, are sulphate-containing members of the pyroaurite group and are analogous to reevesite. The structural formula can be written (Ni 5.55 Mg 0.10 Fe 2.35 3+ )(OH) 16 (SO 4 ) 1.18 . x H 2 O for the Unst material, with sulphate groups replacing the interlayer carbonate groups in reevesite. Microprobe analyses of the Unst material show amounts of SO 3 in excess of that required to balance all trivalent cations and this may be due to the presence of an amorphous nickel sulphate material. We find no evidence for the presence of trivalent nickel in honessite. The Unst material occurs in both 8.8 (honessite) and 11.1 Å (hydrohonessite) forms, depending on composition, humidity, and temperature, similar to carrboydite, motukoreaite, and SO 4 -exchanged takovite. The Wisconsin material occurs only with an 8.8 A basal spacing. The increase from the 7.7 Å basal spacing of reevesite is due to the difference in molecular geometry of carbonate and sulphate groups. The presence of the sulphate molecule is unambiguously shown by the infra-red spectra, and the observed bands are consistent with the sulphate groups lying in the interlayer with their trigonal axes parallel to c . The Unst material is found intimately mixed in variable proportions with reevesite, distributed in patches on chromite, and the mixed nature is revealed by X-ray powder diffraction, by variations in total SO 3 content, and by the presence of absorptions due to both SO 2- 4 and CO 2- 3 in the infra-red spectra.
    Type of Medium: Online Resource
    ISSN: 0026-461X , 1471-8022
    URL: Article
    DOI: 10.1180/minmag.1981.044.335.15
    RVK:
    TE 1000
    Language: English
    Publisher: Mineralogical Society
    Publication Date: 1981
    detail.hit.zdb_id: 2034522-7
    SSG: 13
    Location Call Number Limitation Availability
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    Online Resource
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