Alkali feldspar

The alkali feldspar group are those feldspar minerals rich in the alkali elements, potassium and sodium. The alkali feldspars include albite, anorthoclase, microcline, orthoclase and sanidine.[1] Albite is considered as one of the alkali feldspars according to its chemical composition and it is also the alkali endmember of the plagioclase series.[2]

Potassium and sodium feldspars are not perfectly miscible in the melt at low temperatures, intermediate compositions of the alkali feldspars therefore occur only in higher temperatures environments.[2]

References

  1. ↑ "Alkali Feldspar". mindat.org. Retrieved December 4, 2011.
  2. 1 2 Klein, Cornelis and Cornelius S. Hurlbut, Jr. Handbook of Mineralogy, Wiley, pp. 446-449 (Fig. 11-95 ISBN 0-471-80580-7
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