aplite

This term is used exclusively within the specialized register of geology and petrology. It describes a specific textural and compositional variety of igneous rock, characterized by its pale appearance and fine grain size. In a professional context, it is often used to describe the intrusive veins that cut through coarser rocks like granite.

As a technical classification of rock material, the term is treated as an uncountable mass noun. It refers to the substance of the rock itself rather than individual stones or specimens, meaning it does not typically take a plural form in scientific descriptions.