The Probert Encyclopaedia of Rocks & Minerals

HORNBLENDE

Hornblende is a common member of the amphibole group. It can be told from pyroxene by cleavage and is found in igneous and metamorphic rocks, including often granite. It has the formulae (Ca,Na)2-3(Mg,Fe,Al)5(Al,Si)8O22(OH) 2 and a relative hardness of 6.
Research Hornblende