Analcitic refers to rocks, typically alkaline basalts or syenites, where the mineral analcime is present as a primary crystallization product or a late-stage alteration phase. Recognizing an analcitic composition indicates specific geochemical conditions during magma cooling, usually involving high sodium and water content. It is a key descriptive term for petrologists classifying rare alkaline volcanic suites.
Heard on the job
We mapped a large analcitic basalt flow overlying the main tuff sequence on the eastern ridge.