What is Hornblende?

Hornblende Describes a Group of Minerals
Hornblende is a common name used to describe a group of minerals that individually can only be distinguished through detailed chemical analysis. For this reason they're known collectively as hornblende.
The name mostly applies to dark coloured amphiboles. The chemical composition of this group of minerals varies but they share similar physical properties.
Amphiboles can be found in different types of rock. Their crystal structure can accommodate a wide variety of chemical elements. Some of the most common include hydrogen, oxygen, sodium, potassium, magnesium, aluminum, silicon, calcium, manganese and iron.
The hornblende in our photo is on display in the Harvard Museum of Natural History, Massachusetts, USA. Photo by Stone Mania.