Hostname: page-component-cd9895bd7-gvvz8 Total loading time: 0 Render date: 2024-12-26T09:22:51.605Z Has data issue: false hasContentIssue false
  • English
  • Français

Weathering of Stone Mountain Granite

Published online by Cambridge University Press:  01 January 2024

Willard H. Grant
Willard H. Grant*
Affiliation:
Emory University, Atlanta, Georgia, USA
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The weathering of Stone Mountain Granite (adamellite) forms kaolinite, endellite, allophane and gibbsite of which kaolinite is the most stable. Bulk density ranges from 2.65 in fresh rock to a minimum of 1.48 in saprolite. It is a good index of weathering. Abrasion pH ranges from 5.0 in saprolite to 9.3 in fresh rock, and is directly related to bulk density and the amount of clay mineral. Among the original minerals, biotite is least stable, followed by oligoclase. Residual microcline fragments occur at the base of the B horizon indicating that it is not completely weathered. Muscovite weathers slightly and quartz appears quite stable.

Evidence shows that solution and reconstitution is necessary in the formation of some if not all clay minerals. This is particularly evident in the formation of endellite veins.

Expansion of the rock in the early phases of weathering occurs but does not produce a significant increase in volume.

Type
Symposium on Clay Mineral Transformation
Information
Clays and Clay Minerals (National Conference on Clays and Clay Minerals) , Volume 11 , February 1962 , pp. 65 - 73
Copyright
Copyright © The Clay Minerals Society 1962

References

Blackwelder, E. (1925) Exfoliation as a phase of rock weathering: J. Geol., v. 33, pp. 793806.CrossRefGoogle Scholar
Correns, D. W. and Engelhardt, W. (1938) Neue Untersuchungen über die Verwitterung des Kalifeldspates: Naturwiss., Jg. 26, Heft 9, pp. 137–138.CrossRefGoogle Scholar
Correns, D. W. (1949) Einfuhrung in die Mineralogie: Springer-Verlag, Berlin, 414 p.CrossRefGoogle Scholar
Grant, W. H. (1962) Field excursion, Stone Mountain Lithonia District: Guidebook No. 2, Georgia Dept. of Mines, Mining and Geology, 21 p.Google Scholar
Herrmann, L. A. (1954) Geology of the Stone Mountain Lithonia District: Georgia Geol. Surv., Bull. 61, 139 p.Google Scholar
Hopson, C. A. (1954) Exfoliation and weathering at Stone Mountain, Georgia: Georgia Mineral Newsletter, v. 11, No. 3, pp. 65–79.Google Scholar
Kerr, P. F. and Kulp, J. L. (1948) Multiple differential thermal analysis: Amer. Min-, v. 33, pp. 387–419.Google Scholar
Krauskopf, K. B. (1956) Dissolution and precipitation of silica at low temperatures: Geochim. et Cosmochim. Acta, v. 10, pp. 1–26.CrossRefGoogle Scholar
LeGrand, E. E. (1949) Sheet structure, a major factor in the occurrence of ground water in the granites of Georgia: Econ. Geol., v. 44, pp. 110–118.CrossRefGoogle Scholar
LeGrand, E. E. (1958) Chemical character of water in the igneous and metamorphic rocks of North Carolina: Econ. Geol., v. 53, pp. 178–189.Google Scholar
Mindling, G. W. (1941) Climate of Georgia: Climate and Man, Yearbook of Agriculture 1941, pp. 819–828.Google Scholar
Sand, L. B. and Bates, T. L. (1953) Mineralogy of the residual kaolins of the Southern Appalachians: Amer. Min., v. 38, p. 358.Google Scholar
Stevens, R. E. and Carron, M. K. (1948) Simple field test for distinguishing minerals by abrasion pH: Amer. Min., v. 33, pp. 31–49.Google Scholar
Sudo, T. and Takahashi, H. (1956) Shapes of halloysite particles in Japanese clays: Clays and Clay Minerals, Natl. Acad. Sci.-Natl. Res. Council, Pub. 356, pp. 67–79.Google Scholar