...Herbert Kroll; Hans Ulrich Bambauer; Ulrich Schirmer Abstract The temperatures T diff and T displ of the diffusive transformation high albite–monalbite and the displacive transformation analbite–monalbite were investigated by X-ray powder methods. Alkali feldspars of composition Or 0,5,10,20,30...

... gives the best agreement between the structure model and X-ray intensities. At high temperatures, albite twinning and broadened diffraction peaks make detection of the albite-monalbite transition difficult; however, these single crystals of synthetic high albite (Or 0.5 Ab 98.3 An 1.2 ) were...

... Baskin's suggestion (1956) that the monalbite analbite transformation takes place from nuclei. The persistency of monalbite nuclei at room temperature appears to be a good measure of the original relative disorder states of the anorthoclases. © 1968 Mineralogical Association of Canada 1968...

... modification, monalbite, at approximately 950°C. Copyright © 1985 by the Mineralogical Society of America 1985 ...

... is 1100°±50°C. It is uncertain if monalbite occurs before melting takes place. Good agreement is shown with earlier data obtained by dilatometry by others on low albite, though the present results give axial and angular details previously unavailable, as well as new data for high albite. Various...

... beam crystal centering and its application to high-pressure crystallography. Journal of Applied Crystallography , 12 , 374 –378. Kroll, H., Bambauer, H.U., and Schirmer, U. ( 1980 ) The high albite-monalbite and analbite-monalbite transitions. American Mineralogist , 65 , 1192 –1211. Kroll...

... (analbite-monalbite) ( Kroll et al. , 1980 ; Salje, 1985 ; Salje et al. , 1985 ) and has been defined as a ‘zone centre’ displacive ferroelastic transition. A spontaneous strain at the different temperatures was calculated, taking as reference state for the monoclinic paraphase the same values...

..., Dawei Meng, Yiying Han (2004) Occurrence of “monalbite” in nature: a TEM study. Earth Planet. Sci. Lett, 222,235–241. The monoclinic Na-dominant analog of sanidine is known as a synthetic compound referred to as “monalbite.” The compound has been detected, on a submicrometer scale, coexisting...

... ) at temperatures just below the solidus. Quickly cooled samples are metrically triclinic because of the C 2/ m - C 1̅ displacive phase transition by which monalbite inverts to analbite at T ≈ 1250 K. Their Al,Si distribution, however, remains that of the high-temperature form and is consistent with monoclinic...

... . Perdew J.P. Burke K. Ernzerhof M. ( 1996 ) Generalized gradient approximation made simple . Physical Review Letters , 77 , 3865 – 3868 . Prewitt C.T. Sueno S. Papike J.J. ( 1976 ) The crystal structures of high albite and monalbite at high temperatures . American...

... and monalbite at high temperatures . American Mineralogist , 61 , 1213 – 1225 . Sueno , S. , Prewitt , C.T. , and Ohmasa , M. ( 1980 ) Topotactic decomposition of some silicates . Journal of the Mineralogical Society , 4 , 339 – 363 . Hirai , H. , Sueno , S. , and Nakazawa...

.... , and Pinkerton , A.A. ( 1989 ) Structure of intermediate albite, NaAlSi 3 O 8 . Acta Crystallographica , C45 , 542 – 545 . Prewitt , C.T. , Sueno , S. , and Papike , J.J. ( 1976 ) The crystal structures of high albite and monalbite at high temperature . American Mineralogist , 61...

... stable over 177°C that converts to acanthite at lower temperatures (Emmons et al. , 1926 ); and monalbite, NaAlSi 3 O 8 a polymorph of albite with monoclinic symmetry that is stable under equilibrium conditions at temperatures 980–1060°C (Winter et al. , 1979 ). An example of a paramorph is beta...

...! Selected publications Brown , W.L. ( 1960 ): X-ray studies in the plagioclases. Part 1. Lattice changes in heat-treated plagioclase – the existence of monalbite at room temperature. Part 2. The crystallographic and petrologic significance of peristerite unmixing in the acid plagioclases . Zeit...

... and symmetry changes from triclinic C 1̅ to monoclinic C 2 /m . The monoclinic phase is known as monalbite, which was recently found as submicrometer inclusions in jadeite within quartzite from the Dabie ultrahigh-pressure metamorphic terrane ( Wu et al. , 2004 ). Besides the above polymorphs...

...., and Schirmer, U. ( 1980 ) The high albite-monalbite and analbite-monalbite transitions. American Mineralogist , 65 , 1192 –1211. Kroll, H., Schmiemann, I., and von Coelln, G. ( 1986 ) Feldspar solid solutions. American Mineralogist , 71 , 1 –16. Kusatz, B., Kroll, H., Kaiping, A., and Pentinghaus...

... transition temperature . Am. Mineral. , 93 , 558 – 564 . Kroll , H. , Bambauer , H.-U. , Schirmer , U. ( 1980 ): The high albite–monalbite and analbite–monalbite transitions . Am. Mineral. , 65 , 1192 – 1211 . Kronenberg , A.K. , Yund , R.A. , Rossman , G.R...

... . Vogt , J.H.L. ( 1921 ): The physical chemistry of the crystallization and magmatic differentiation of igneous rocks . J. Geol. , 29 , 318 – 350 . Winter , J.K. , Okamura , F.P. , Ghose , S. ( 1979 ): A high-temperature structural study of high albite, monalbite...