amphibole
/ˈamfɪbəʊl
/noun [mass noun]
Any of a class of rock-forming silicate or aluminosilicate minerals typically occurring as fibrous or columnar crystals: acid rocks consist mostly of quartz and feldspars, with a little mica or amphibole...
- During obduction, mantle-derived magmas most likely evolved to granitic compositions by assimilation of sediments and by fractional crystallization of amphibole, feldspar, titanite and allanite.
- Associated with the fayalite are quartz, amphibole, and magnetite.
- They contain sulfide minerals as well as metamorphic minerals that include cordierite, gahnite, epidote, garnet, amphiboles, schorl, and many others.
Origin
Early 19th century: from French, from Latin amphibolus 'ambiguous' (because of the varied structure of these minerals), from Greek amphibolos, from amphi- 'both, on both sides' + ballein 'to throw'.