Abstract

Cancrinites of compositions 3NaAlSiO 4 XCaCO 3 ,3NaAlSiO 4 XCa(OH) 2 and 3NaAlSiO 4 XK 2 O 3 were made in the 200 degrees to 800 degrees C range at 10,000 to 30,000 psi of water pressure. The first two compositions did not dissociate at upper pressure and temperature limits but the third composition dissociated to nepheline and probably K 2 CO 3 at 425-475 degrees C. Synthetic 3NaAlSiO 4 XNa 2 CO 3 , 3NaAlSiO 4 XNaHCO 3 , and 3NaAlSiO 4 XKHCO 3 cancrinites were made also. Cell edges (+ or -0.02 A) for the six compositions given above and in the same order are: a=12.59, 12.60, 12.73, 12.67, 12.67, 12.73, and c=5.17, 5.14, 5.18, 5.18, 5.16, 5.20 with Vol. (A) - 710, 707, 727, 717, 728. Analcite and a carbonate or hydroxide appeared at low temperatures with cancrinite. Cell edges for four unanalysed natural specimens are given.

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