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Glossary

A (6) | B (6) | C (10) | D (11) | E (7) | F (10) | G (10) | H (1) | I (2) | J (1) | L (7) | M (12) | O (3) | P (11) | Q (3) | R (9) | S (23) | T (5) | U (3) | W (1)
Hornblende

The most common mineral of the amphibole group, a complex hydrous aluminum silicate in which calcium, sodium, iron, and magnesium are present in varying amounts; commonly black, dark-green, or brown and occurring in distinct long, slender crystals or in columnar, fibrous, or granular forms. It is a primary constituent of many felsic and intermediate igneous rocks, and, while less common, in mafic igneous rocks, and it is a common constituent in metamorphosed mafic rocks, such as amphibolite.