|a black or greenish-black mineral of the amphibole group, found in igneous and metamorphic rocks. Composition: calcium magnesium iron sodium aluminium aluminosilicate. General formula: (Ca,Na)2.3(Mg,Fe,Al)5Si6(Si,Al)2O22(OH)2|
|[C18: from German Horn horn + |
|hornblende (hôrn'blěnd') Pronunciation Key
A common, green to black mineral of the amphibole group. It has a variable composition and occurs in monoclinic crystals with a hexagonal cross-section, in fibrous forms, or in granular forms. Hornblende is found in many metamorphic and igneous rocks. Chemical formula: (Ca,Na)2-3(Mg,Fe,Al)5(Al,Si)8O22(OH)22.