1976 Volume 8 Issue 3 Pages 171-183
Bicchulite was synthesized from gehlenite solid solutions with a composition range from Ak0Ge100 to Ak40Ge60. Upper limits of the stability field of bicchulite at 1 kbar water pressure were found to be at 635°C for Ak0Ge100, 610°C for Ak20Ge80, and 605°C for Ak40Ge60. Gehlenite with the akermanite components less than 20% decomposes to bicchulite±idocrase±xanthophyllite below the temperature of the stability limit, while gehlenite with the akermanite component more than 30% breaks down at a temperature higher than the temperature of bicchulite stability, 630°C for Ak30Ge70 and 680°C for Ak50Ge50, forming idocrase+xanthophyllite±monticellite. Xanthophyllite obtained in the experiments is stable only at temperatures above about 400°C. Below that temperature it changes to hydrogrossular.
Some natural specimens were also studied for geological applications.