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) 5 Si 6 (Si,Al) 2 O 22 (OH) 2
1796, from German Hornblende, from horn (see horn (n.)) + blende (see blende).
The term "Hornblende" is an old German name for any dark, prismatic crystal found with metallic ores but containing no valuable metal (the word "Blende" indicates "a deceiver") [Herbert Bucksch, "Dictionary Geotechnical Engineering," 1995]
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.