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Stilbite is a low-temperature secondary hydrothermal mineral. It occurs in the amygdaloidal cavities of basaltic volcanic rocks, in andesites, gneiss and hydrothermal veins. It also forms in hot springs deposits, and as a cementing agent in some sandstones and conglomerates. Stilbite has not been found in sedimentary tuff deposits or deep-sea deposits. Associated minerals are other zeolites, prehnite, calcite and quartz.
The open channels in the stilbite structure act like a molecular sieve, enabling it to separate hydrocarbons in the process of petroleum refining.