hornblende

This term is used exclusively within the specialized register of geology and mineralogy. It describes a specific group of amphibole minerals, and its usage is strictly technical, appearing in scientific reports, academic textbooks, and field notes rather than in general conversation.

As a mineral name, it functions as a mass noun referring to the substance itself. While one might discuss different types or varieties of hornblende, the word does not typically take a plural form in professional geological contexts.