Any of a large group of structurally similar silicate minerals, such as hornblende, that have a crystalline structure consisting of a double chain of linked SiO4 units and that contain various combinations of sodium, calcium, magnesium, iron, and aluminum. Several varieties of asbestos are fibrous forms of amphiboles.
[French, from Late Latin amphibolus, ambiguous, from Greek amphibolos, doubtful, from amphiballein, to throw on either side : amphi-, amphi- + ballein, to throw; see gwelə- in the Appendix of Indo-European roots.]
am′phi·bolic (-bŏlĭk) adj.
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