Abstract
The activity of the jadeite (NaAlSi2O6) component in synthetic pyroxenes on the binary join NaAlSi2O6-CaMgSi2O6 has been measured at 600° C by equilibration of pyroxene with quartz and high albite in hydrothermal experiments. The results are in good agreement with recent calorimetry (Wood et al. 1980) for pyroxenes not close to the Jd50Di50 composition for which a considerable degree of short range ordering on the omphacite scheme is indicated by the activity measurements. For compositions close to Jd50Di50, the activity of the jadeite component is approximately equal to its mole fraction.
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References
Bell PM, Davis NL (1969) Melting relations in the system jadeite-diopside at 30 and 40 kilobars. Am J Sci 267-A:17–32
Carpenter MA (1978) Kinetic control of ordering and exsolution in omphacite. Contrib Mineral Petrol 67:17–24
Carpenter MA (1979) Omphacites from Greece, Turkey, and Guatemala: composition limits of cation ordering. Am Mineral 64:102–108
Carpenter MA (1981) Time-temperature-transformation (TTT) analysis of cation disordering in omphacite. Contrib Mineral Petrol 78:433–440
Clark JR, Papike JJ (1968) Crystal-chemical characterization of omphacites. Am Mineral 53:840–868
Essene EJ, Fyfe WS (1967) Omphacite in Californian metamorphic rocks. Contrib Mineral Petrol 15:1–23
Fleet ME, Herzberg CT, Bancroft GM, Aldridge LP (1978) Omphacite studies, 1. The P2/n→C2/c transformation. Am Mineral 63:1100–1106
Ganguly J (1973) Activity-composition relation of Jadeite in omphacite pyroxene. Earth Planet Sci Lett 19:145–153
Holland TJB (1979) Reversed hydrothermal determination of jadeite-diopside activities. EOS, Trans Am Geophys Union 60:405
Holland TJB (1980) The reaction albite=jadeite+quartz determined experimentally in the range 600–1,200° C. Am Mineral 65:129–134
Jenkins DM, Newton RC (1979) Experimental determination of the spinel peridotite to garnet peridotite inversion at 900° C and 1,000° C in the system CaO-MgO-Al2O3-SiO2, and at 900° C with natural garnet and olivine. Contrib Mineral Petrol 68:407–419
Kushiro I (1969) Clinopyroxene solid solutions formed by reactions between diopside and plagioclase at high pressures. Mineral Soc Am Sp Pap 2:179–191
Newton RC, Smith JV (1967) Investigations concerning the breakdown of albite at depth in the earth. J Geol 75:268–286
Robie RA, Hemingway BS, Fisher JR (1979) Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar (105 pascals) pressure and at higher temperatures. USGS Bull 1452
Wood BJ (1978) Reactions involving anorthite and CaAl2SiO6 pyroxene at high pressures and temperatures. Am J Sci 278:930–942
Wood BJ, Holland TJB, Newton RC, Kleppa OJ (1980) Thermochemistry of jadeite-diopside pyroxenes. Geochim Cosmochim Acta 44:1363–1371
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Holland, T.J.B. The experimental determination of activities in disordered and short-range ordered jadeitic pyroxenes. Contr. Mineral. and Petrol. 82, 214–220 (1983). https://doi.org/10.1007/BF01166616
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DOI: https://doi.org/10.1007/BF01166616