HornblendeHornblende is a member of the amphibole group of more complex silicates, in which the tetrahedra are linked to form a continuous chain twice the width of the pyroxene chains. For this reason they are often referred to as double chain silicates. Like the pyroxenes, they can be subdivided into those with orthorhombic symmetry (orthoamphiboles) and those with monoclinic symmetry (clinoamphiboles). Hornblende is the most common of the clinoamphiboles.
Chemical composition - Ca
2(Mg, Fe, Al)
Other specimens - Click the thumbnails to enlarge