Hornblende \Horn"blende`\, n. [G., fr. horn horn + blende
blende.] (Min.)
The common black, or dark green or brown, variety of
amphibole. (See Amphibole.) It belongs to the aluminous
division of the species, and is also characterized by its
containing considerable iron. Also used as a general term to
include the whole species.
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Hornblende schist (Geol.), a hornblende rock of schistose
structure.
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Amphibole \Am"phi*bole\ ([a^]m"f[i^]*b[=o]l), n. [Gr.
'amfi`bolos doubtful, equivocal, fr. 'amfiba`llein to throw
round, to doubt: cf. F. amphibole. Ha["u]y so named the genus
from the great variety of color and composition assumed by
the mineral.] (Min.)
A common mineral embracing many varieties varying in color
and in composition. It occurs in monoclinic crystals; also
massive, generally with fibrous or columnar structure. The
color varies from white to gray, green, brown, and black. It
is a silicate of magnesium and calcium, with usually
aluminium and iron. Some common varieties are tremolite,
actinolite, asbestus, edenite, hornblende (the last
name being also used as a general term for the whole
species). Amphibole is a constituent of many crystalline
rocks, as syenite, diorite, most varieties of trachyte, etc.
See Hornblende.
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