2020 Volume 70 Issue 2 Pages 89-99
Natural zeolites are produced in volcanic rocks and sedimentary rocks (pyroclastic rocks). Almost all zeolites in the volcanic rocks, which are in the primary occurrence, are secondary minerals due to alteration. The large zeolite crystals found in the veins and druses of volcanic rocks are formed by hydrothermal alteration or diagenesis. Zeolites in sedimentary rocks originate from highly reactive volcanic glass and are formed in high-alkaline environments or high-temperature environments. The formation of high-alkaline environment is classified into saline alkaline lakes, surface weathering of arid regions, and infiltration of rainwater. Zeolites formed by heat source are classified into hydrothermal alteration and diagenesis. In addition, there is a complex mixture cause of diagenesis and high-alkaline environment. An occurrence not classified in this category is zeolite in deep-sea sediments.
