Compositional controls on the a and b cell dimensions of 2M1 muscovite
Guidotti, Charles V.; Sassi, Francesco P.; Blencoe, James G.
published: Mar 21, 1989
ArtNo. ESP147050101010, Price: 29.00 €
Abstract Chemical and X-ray diffraction data for 2M1 muscovites have been evaluated with the aim of quantifying the changes in α and b that occur with substitution of Mg, Fe2+ and Fe3+ for A1VI. Examination of old (63 muscovites) and newly acquired (79 muscovites) data for both natural and synthetic 2M1 muscovites reveals that α and b decrease with increasing Na / (Na + K) ratio. However, the effect of Na ⇆ K substitution becomes important only when Na / (Na + K) exceeds 15 mole percent. Diagrams and regression equations for Na / (Na + K) ≤ 0.15 indicate that α and b vary linearly with Σ (Mg + Fe2+ + Fe3+), Σ (A1IV + A1VI), and Si: α = 5.1831 + 0.0270 Σ (Mg + Fe2+ + Fe3+) r = 0.907 n = 88 α = 5.2781 - 0.0157 Σ (A1IV + A1VI) r = -0.907 n = 88 α = 4.9312 + 0.0422 Si r = 0.845 n = 88 b = 8.9931 + 0.0440 Σ (Mg + Fe2+ + Fe3+) r = 0.914 n = 88 b = 9.1490 - 0.0258 Σ (A1IV + A1VI) r = -0.921 n = 88 b = 8.5966 + 0.0666 Si r = 0.872n = 88