“…The high percentage of accessible reflections along with the effectiveness of the 'corrections' for absorption are reflected in the high precision of the results (Tables 2 a-5 a): They are in excellent agreement with previous ambient-pressure studies (Y oun g and Post, 1962;Smith and Alexander, 1963;Zachariasen and Plettinger, 1965;Le Page and Donnay, 1976;Le Page, Calvert and Gabe, 1980;Levien, Prewitt and Weidner, 1980;Wright and Lehmann, 1981;Lager, Jorgensen and Rotella, 1982;Will, Parrish and Huang, 1983;Ogata, Takeuchi and Kudoh, 1987;Hazen et al, 1989;Kihara, 1990), and the high-pressure results have higher precision than those from any other previous high-pressure study (Jorgensen, 1978;D'Amour, Denner and Schulz, 1979;Levien, Prewitt and Weidner, 1980;Ogata, Takeuchi and Kudoh, 1987;Hazen et al, 1989). Table 5 a gives atomic distances and bond angles as calculated with the program BONDLA of the X-RAY system (Stewart et al, 1972).…”