NATROLITE THOMSONITE INTERGROWTHS FROM BASALTIC ROCKS OF DECCAN TRAPS(WESTERN INDIA)/

Natrolite/thomsonite intergrowths developed inside basalt cavities fro m Deccan Traps (Western India), described for the first time, have bee n investigated using a combination of microscopic, diffraction, spectr oscopic and thermal techniques. The XRD and chemical analyses showed t hat the zeolitic material consisted of natrolite and thomsonite. The S i-29 MAS NMR and FT-IR measurements indicated the coexistence of two d iscernible zeolite phases in the material. The main endothermic peaks of the material were recorded at 323 degrees C, 380 degrees C and 420 degrees C. The SEM-EDS study proved that the two minerals form epitaxi al overgrowths joined at an interface parallel to their c axes and int ergrowths joined at an interface unparallel to the c axes. The formati on of the two-phase natural zeolitic material is mainly attributed to crystallographic similarities between the two phases and their crystal lization under the same conditions.