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Studies on the zeolites. Part VII1. ‘Clinoptilolite’, a silica-rich variety of heulandite.

Published online by Cambridge University Press:  14 March 2018

Max H. Hey  and
F. A. Bannister
Max H. Hey
Affiliation:
Mineral Department of the British Museum of Natural History
F. A. Bannister
Affiliation:
Mineral Department of the British Museum of Natural History
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Extract

In 1890, L. V. Pirsson 2 described under the name of mordenite a crystalline mineral, isomorphous with heulandite, occurring in a highly weathered amygdaloidal basalt in the Hoodoo Mts., Wyoming. His analysis (1, table I) showed that the mineral had a composition near that of the original mordenite of H. How (1864) and his assumption that it represented a platy-crystalline phase of that normally fibrous mineral was generally accepted.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 23 , Issue 145 , June 1934 , pp. 556 - 559
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1934

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Footnotes

page 556 note 1

Part VI. Edingtonite. Min. Mag., 1934, vol. 23, p. 483

References

page 556 note 2 Pirsson, L. V., Amer. Journ. Sci., 1890, ser. 3, vol. 40, p. 232.CrossRefGoogle Scholar

page 556 note 3 Walker, T. L. and Parsons, A. L., Univ. Toronto Studies, Geol. Ser., 1922, no. 12, p. 61.Google Scholar [M.A. 2-55.]

page 556 note 4 Schaller, W. T., Amer. Min., 1932, vol. 17, p. 128 Google Scholar; also in abstract in Amer. Min., 1923, vol. 8, p. 93, and quoted in C. S. Ross and E. V. Shannon, Proc. U.S. Nat. Mus., 1925, vol. 64, p. 3. [M.A. 5-147, 2-301 ; Min. Mag. 20-450.]

page 556 note 5 Bramlette, M. N. and Posnjak, E., Amer. Min., 1933, vol. 18, p. 167 Google Scholar. [M.A. 5-357.]

page 557 note 1 The present authors find n 1·48 approx., birefringence low, extinction undulatory, Bxo (?) ⊥ L b (010), probably optically negative.

page 557 note 2 Part V of this series, Min. Mag., 1933, vol. 23, p. 421 ; compare Taylor, W. H., Zeits. Krist., 1933, vol. 84, p. 373. [M.A. 5-354.]Google Scholar

page 557 note 3 Part II of this series, Min. Mag., 1932, vol. 23, p. 51.

page 557 note 4 It appears probable from the data so far available that in many zeolites the birefringence is largely due to polarization by the charged aluminium atoms, and their replacement by silicon appears as a rule to decrease the birefringence very markedly.

page 558 note 1 W. T. Schaller, as quoted by Bramlette and Posnjak, considers that ~he differences in chemical composition between the Arizona and Wyoming material are unimportant. In the present authors' opinion, the differences are well outside the probable experimental error; moreover, Schaller does not give any grounds for his statement that the Arizona material contained 5 o of clay. The analysis itself affords no internal evidence of impurity ; and even 5 % of clay would not account for the differences.

page 558 note 2 For the unit cell contents of heulandite, compare Wyart, J., Compt. Rend. Acad. Sci. Paris, 1930, vol. 190, p. 1564. [M.A. 4-369.]Google Scholar The figures there given are half the unit cell contents, the end-centred cell containing two ' structural units '.

X-ray photographs of mordenite and ptilolite are quite different from those of heulandite, and appear to be identical ; the name mordenite has priority.