Composite Crystal Phases of Authigenic Heulandite-clinoptilolite from Sandstones and Its Crystal-chemical Significance

사암에서 산출되는 속성 기원 휼란다이트-클리놉틸로라이트의 복합 결정상의 그 결정화학적 의의

The coarse-grained (0.05∼0.2mm) zeolites occur as the single-crystal cement in the sandstones of the Chunbuk Formation in the Pohang area. The zeolite cements unusually consist of the composite phases of heulandite and clinoptilolite and in a crystal. The zeolite crystals show chemical zoning ranging from 3.56 to 4.10 in Si/(Al+Fe), and tend to become continuously more silicic and alkalic from the margin toward inside of the crystal. The DTA and high-temperature XRD analyses also show complex patterns of both zeolites. Such a composite crystal showing chemical zoning and complex thermo-chemical behaviors indicates that heulandite and clinoptilolite are constituting a solid solution resulted from the coupled substitution of K+Si4+=Ca2+Al3+.