Abstract
Chemical-optical and X-ray analysis of some perthite groups, from cristalline rock massifs, came into evidence that in perthites with the same order degree of Si/Al distribution, the observed variations of 2VX are strictly related to the Na content in the potassic phase; i.e. 2VX decreases when Ab mixed in the K-phase increases.
This fact suggests that for any Si/Al, distribution, not in equilibrium, exists a certain range of non equilibrium mixing between Or and Ab.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bambauer, H. U., u. F. Laves: Zum Adularproblem. I. Adular vom Val Casatscha: Mimetischer Lamellenbau, Variation von Optik und Gitterkonstanten und ihre genetische Deutung. Schweiz. mineral. petrog. Mitt. 40, H. 2, 177–205 (1960).
Chayes, E.: The Petrographic modal analysis. New York: John Wiley & Sons. 1956.
Goldsmith, J. R., and F. Laves: The microcline-sanidine stability relations. Geochim. et Cosmochim. Acta 5, 1–19 (1954).
—: Potassium feldspars structurally intermediate between microcline and sanidine. Geochim. et Cosmochim. Acta 6, 100–118 (1954).
—: The sodium contents of microclines and the microcline-albite serie. Cursillos y confs inst. Lucas Mallada 8, 81–96 (1961).
Laves, F.: Phase relations of the alkali feldspars. I. Introductory remarks. II. The stable and pseudostable phase relations in the alkali feldspars system. J. Geol. 60, 436–450, 549–576 (1952).
Smith, J. V., and W. S. Mackenzie: The alkali feldspars. I. Orthoclase microperthites. Am. Mineralogist 40, 707–732 (1955).
—: The alkali feldspars. III. An optical and X-ray study of high temperature feldspars. Am. Mineralogist 41, 405–427 (1956).
—: The alkali feldspars. IV. The cooling history of high-temperature sodium-rich feldspars. Am. Minrealogist 43, 872–889 (1958).
—: The alkali feldspars. V. Orthoclase and microcline perthites. Am. Mineralogist 44, 1169–1186 (1959).
Spencer, E.: The potash-soda feldspars. I. Thermal stability. Mineral. Mag. 24, 534–494 (1937).
Tuttle, O. F.: Optical studies of alkali feldspars. Am. J. Sci., Bowen volume, 553–567 (1952).
Regional References
De Pol, C., e M. Fiorentini Potenza: La micropertite nel “protogino” del Monte Bianco (Tratto italiano della galleria). Rend. Accad. Ist. Lomb. Sci. e Lett. 98, 407–436 (1954).
Fiorentini Potenza, M.: Evoluzione strutturale, dispersione ottica ed altri caratteri del K-feldspato nelle zone differenziate della massa intrusiva della Valle del Cervo (Biella). Rend. Accad. Ist. Lomb. Sci. e Lett. 95, 807–826 (1961).
Marinelli, G.: Le intrusioni terziarie dell'isola d'Elba. Atti soc. toscana sci. nat. 66, 50–253 (1959).
—: L'intrusione terziaria di Gavorrano. Atti soc. toscana sci. nat. 68, 117–194 (1961).
Wright, T. L.: The alkali feldspars of the Tatoosh pluton in Mount Rainier National Park. Am. Mineralogist 49, 715–735 (1964).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Potenza Fiorentini, M. Non-equilibrium mixing in natural alkali feldspars. Contr. Mineral. and Petrol. 21, 1–8 (1969). https://doi.org/10.1007/BF00377415
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00377415