Hostname: page-component-76fb5796d-45l2p Total loading time: 0 Render date: 2024-04-25T14:32:01.072Z Has data issue: false hasContentIssue false
  • English
  • Français

On the nature of withamite from Glen Coe, Scotland (With Plate IV.)

Published online by Cambridge University Press:  14 March 2018

C. Osborne Hutton
C. Osborne Hutton*
Affiliation:
Department of Mineralogy and Petrology, University of Cambridge
Get access Rights & Permissions [Opens in a new window]

Extract

In 1824 Henry Witham discovered a beautiful red epidote mineral in the lavas of Glen Coe, Argllshire, which was described by Brewster under the name withamite. An analysis was made by Coverdale of obviously highly impure material, but later a more complete one was carried out by Heddle on carefully hand-picked mineral. Heddle admits, however, that his analysis shows ‘by no means a satisfactory agreement with the composition of epidote’, and from his figures it would seem very likely that his analysed material was also impure. In the Glen Coe Geological Survey Memoir no further data were recorded of this mineral, Heddle's analysis and description merely being quoted.

The writer visited Glen Coe and collected material in a cutting on the new road, approximately 5½ miles west of King's House (Geological Survey, sheet 53), where it is fairly well exposed. It occurs in a fine-grained, rather altered andesitic rock, as narrow veinlets up to 120 mm. in length and 50 mm. in width ; also as infillings of vesicles. The veinlets may be straight or highly irregular; in the former case they possibly follow joint-planes, for the rock will often fracture along such a plane, producing one or two surfaces covered with the red epidote mineral. The vesicles vary greatly in size from approximately 0·3 to 70 mm., and in the larger ones calcite is a common associate.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 25 , Issue 162 , September 1938 , pp. 119 - 124
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1938

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

page 119 note 1 Brewster, D., Description of withamite, a now mineral species found in Glenco. Edinburgh Journ. Sci., 1825, col. 2, pp. 218–221.Google Scholar

page 119 note 2 Thomson, T., Outlines of mineralogy, geology and mineral analysis. London, 1836, col. 1, p. 377.Google Scholar

page 119 note 3 Heddle, M. F., Minerals new to Britain. Min. Mag., 1882, vol. 5, pp. 1–25 (withamite, p. 15).CrossRefGoogle Scholar

page 119 note 4 Heddle, M. F., Chapters on the mineralogy of Scotland. Trans. Roy. Soc. Edinburgh, 1899, col. 39, p. 355.Google Scholar

page 119 note 5 Bailey, E. B. and Maufe, H. B., The geology of Ben Nevis and Glen Coe. Mem. Geol. Surv. Scotland, (sheet 53), 1916, p. 179.Google Scholar

page 120 note 1 Lausen, C., Piedmontite from the Sulphur Spring valley, Arizona. Amer. Min., 1927, vol. 12, pp. 283–287. [Min. Abstr. 3–456.]Google Scholar

page 120 note 2 Guild, F. N., Piedmontite in Arizona. Amer. Min., 1935, vol. 20, pp. 679–692 [M.A. 6–380.]Google Scholar

page 120 note 3 Yamasaki, N., On the piedmontite-rhyolite from Shinano. Neues Jahrbuch Min., 1898, vol. 2, pp. 253–254.Google Scholar

page 121 note 1 Machatschki, F., Die kristallochemischen Boziehungen zwischen Epidot-Zoislt und Orthit-Allanit. Centr. Min., Abt. A, 1930, pp, 89–96. [M.A. 4–357.]Google Scholar

page 122 note 1 Hillebrand, W. F. and Lundell, G. E. F., Applied inorganic analysis. New York, 1929.Google Scholar

page 122 note 2 Smethurst, A. F., Anomalies in the analytical determination of water in epidote. Min. Mag., 1935, vol. 24, pp. 173–179.CrossRefGoogle Scholar

A few grains gave a γ value as high as 1·767±0·002.

page 123 note 1 Winchell, A. N., Elements of optical mineralogy. New York, 1933, pt. 2, p. 313.Google Scholar

page 123 note 2 Turner, F. J., Note on the occurrence of piedmontite in quartz-muscovite-schist from Shotover valley, western Otago, New Zealand. Min. Mag., 1933, vol. 23, pp. 416–418.CrossRefGoogle Scholar

page 123 note 3 Laeroix, s A.,Propriétés optiques de la withamite. Bull. Soc. Franç. Min., 1886, vol. 9, pp. 75–77.Google Scholar Matériaux pour la minéralogie de la France. IV. Épidote manganésifère (piédmontite) de l'île de Groix. Ibid., 1888, vol. 11, pp. 148–149.

page 123 note 4 Williams, G. H., Piedmontite and scheelite from the ancient rhyolites of South Mountain, Pennsylvania. Amer. Journ. Sci., 1893, ser. 3, vol. 46, pp. 50–57.CrossRefGoogle Scholar

page 123 note 5 C. Lausen, loc. cit.

page 123 note 6 F. N. Guild, loc. Cit

page 124 note 1 Fe2O3 content was estimated by moans of an approximate determination of the birefringence with a quartz wedge.