Geologists use this term to describe porphyritic or basaltic rocks where a matrix of glass or cryptocrystalline material occupies the angular gaps between plagioclase laths. It indicates rapid cooling of the magma after the initial phenocrysts had already formed, locking the remaining melt into a glassy state.
Heard on the job
The thin section clearly shows an intersertal texture, confirming the rapid quenching of the basalt flow.