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On Strüverite and its relation to Ilmenorutile

Published online by Cambridge University Press:  14 March 2018

G. T. Prior  and
F. Zambonini
G. T. Prior
Affiliation:
Mineral Department of the British Museum
F. Zambonini
Affiliation:
Mineral Department of the British Museum
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Extract

The mineral strüverite occurs as a rare accessory constituent of the pegmatite which is found in large detrital masses in the neighbourhood of Craveggia (Val Vigezzo, northern Piedmont), namely on the Piano dei Lavonchi and in other localities on the eastern slope of the mountain across which runs the road from Vasca to the Alp Marco. In this pegmatite Professor G. Spezia in 1882 noted the occurrence of beryl, and two years later Professor G. Strüver that of columbite, a mineral which had not hitherto been found in the Alps. Still later, notices of other rare minerals from the pegmatiie were published by Professor A. Piccini and Professor A. Cossa.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 15 , Issue 68 , April 1908 , pp. 78 - 89
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1908

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References

Page 78 note 1 A detailed description of the occurrence and of the physical characters of strüverite has been published by ene of us : Ferruccio Zambonini, ‘Strüverite, un nueve minerale.’ Rend. R. Accad. Sci. Napoli, 1907, ser. 3, vol. xiii, pp. 35-41. The details of the chemical examination are given for the first time in the present paper.

Page 78 note 2 Spezia, G., Atti R. Accad. Sci. Terino, 1882, vol. xvii, p. 769 Google Scholar.

Page 78 note 3 Strüver, G., Rend. R. Accad. Lincei, Roma, 1884, ser. 4, vol. i, p. 8 Google Scholar.

Page 78 note 4 Piccini, A., Rend. R. Accad. Lincei, Roma, 1886, ser. 4, vol. ii; sem. 2, p. 46 Google Scholar.

Page 78 note 5 Cossa, A., Gazz. chim. ital., 1887, vol. xvii, p. 31 Google Scholar.

Page 80 note 1 On the homogeneity of the mineral see the previous paper by Zambonini, loc. cit., p. 44

Page 80 note 2 Warren, C. H., Amer. Journ. Sci., 1906, vol. xxii, p. 520 CrossRefGoogle Scholar, or Chem. News, 1906, vol. xciv, p. 298.

Page 82 note 1 The idea that zirconium was present as an essential constituent of the mineral was unfortunately communicated to Dr. Zambonini before the completion of the analyses, and was published by him in the paper to which reference has already been made (see footnote, p. 78). The chemical data there given therefore need correction.

Page 82 note 2 Ruer, R., Zeits. anorg. Chem., 1905, vol. xlvi, p. 456.CrossRefGoogle Scholar

Page 82 note 3 Faber, P., ‘Ueber das Wesen des sechswertigen Titans.’ Zeits. anal. Chem., 1907, vol. xlvi, pp. 277–291.CrossRefGoogle Scholar

Page 82 note 4 Hillebrand, W. F., ‘The analysis of silicate and carbonate rocks.’ United States Geol. Survey, 1907, Bull. no. 305, p. 119.Google Scholar

Page 83 note 1 When a few drops only of ‘perhydrol’ are added to a concentrated solution of zirconium sulphate, the precipitate first formed dissolves on shaking, and a permanent precipitate only results after the addition of a considerable excess of the hydrogen peroxide.

Page 83 note 2 Giles, W. B., Chem. News, 1907, vol. xcv, pp. 1 and 37Google Scholar

Page 84 note 1 A third determination of the titanic acid 7 made on 0.0747 gram of material 7 gave the number 40.72.

Page 84 note 2 Of this percentage of niobic and tantalic acids, 27.85 passed into solution with the titanic acid.

Page 84 note 3 The experiments described on pp. 81, 83 indicate that the tantalic and niobic acids are present in about equal parts by weight.

Page 85 note 1 Brögger, W. C., ‘Die Mineralien der südnorwegischen Granit-Pegmafitgäinge. I. Niobate, Tantalate, Titanate und Titanoniobate.’ Videnskabs-Selskabets Skrifter, Math.-Naturv. Klasse, 1906, no. 6, p. 41.Google Scholar

Page 87 note 1 Of this percentage of niobic acid as much as 25.22 passed into solution with the titanic acid. The loss in tile analysis is probably partly due to loss of niobie acid in washing the ammonia precipitate, and partly to loss on evaporation with hydrofluoric acid in testing for tantalic acid by Marignac's method : no needles of the tantalum salt were obtained.

Page 87 note 2 Determined on 0.5310 gram of material. The specific gravity of a mixture (corresponding to the above analysis) of 55 parts of rutile (sp. gr. = 4.2), 19 parts of tantalite (sp. gr. = 7.3), and 28 parts of columbite (sp. gr. = 5.3) would be 5-10.

Page 87 note 3 Determined on 1.3497 gram of material. The specific gravity of a mixture (corresponding to the above analysis) of 55 parts of rutile (sp. gr. = 4.2) and 45 parts of columbite (sp. gr. = 5.3) would be 4.69.

Page 88 note 1 The experience of the solubility of niobic and tantalic acids in presence of excess of titanic acid, which was gained in the analyses of strüverite, naturally suggested the idea that possibly the iron in ferriferous rutiles might be combined with niobic and tantalic acids, and that these acids might have been previously overlooked. A colorimetric determination, however, of the titanic acid in a specimen of nigrine from Transylvania gave the number 96 per cent., and thus lent no support to this view.

Page 88 note 2 This view has already been expressed by Prandtl, W., Zeits. Kryst. Min., 1905, vol. xl, p. 995 Google Scholar

Page 88 note 3 W. C. Brögger, 1906, loc. cit.