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The Holmes effect and the lower limit of modal analysis

Published online by Cambridge University Press:  14 March 2018

F. Chayes*
Affiliation:
Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C., U.S.A.

Summary

Thin-section analysis is essentially an areal measurement, the measurement area usually being the upper surface of the section. If transmitted light is used for the measurement, the apparent areas of opaque grains will in general be somewhat larger than their true areas on the measurement surface. For strictly spherical opaque particles in a transparent matrix the expected excess of apparent over true area is shown to be (πr2k)/(2r + k) where r is the spherical radius and κ is the thickness of the thin section. A table shows the relation between true and apparent area as a function of r/k.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1956

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References

page 276 note 1 Petrographic methods and calculations. Thomas Murby and Co., London, 1920, p. 317.

page 280 note 1 Min. Mag., 1952, vol. 29, p. 833.