This is a silica-undersaturated intrusive igneous rock that forms from alkaline magmas. It is primarily composed of calcium-rich plagioclase, augite, olivine, and the zeolite mineral analcime. Geologists identify it in sills and dykes, where it represents a specific type of late-stage magmatic crystallization in continental rift settings.
Heard on the job
We mapped a massive teschenite sill cutting straight through the local sandstone sequence.